Letters written by Leeuwenhoek

Alle de Brieven / Collected Letters has over 350 letters. However, only those in this chronology that Leeuwenhoek designated Letter 1, Letter 2, etc. did he consider to contain publishable microscopic observations.

Date
April 28, 1673 Wrote Letter L-001 of 1673-04-28 to Henry Oldenburg about mould and a bee's stinger and eye
August 15, 1673 Wrote Letter L-002 of 1673-08-15 to Henry Oldenburg about the bee, the movement of liquids in wood and food in a louse, and the composition of air
November 8, 1673 Wrote Letter L-003 of 1673-11-08 to Henry Oldenburg about globules in milk and in blood and his theory on the structure and growth of hair and of tumours
April 5, 1674 Wrote Letter L-005 of 1674-04-05 to Constantijn Huygens about globules in milk and blood and the growth of hair; first mention of red blood corpuscles
April 7, 1674 Wrote Letter L-006 of 1674-04-07 to Henry Oldenburg about globules in milk and blood, the growth of hair and nails, and the anatomy of a louse
April 16, 1674 Wrote Letter L-008 of 1674-04-16 to Henry Oldenburg about the delivery of his letters and asking Oldenburg to befriend van Conincxbrugh
April 24, 1674 Wrote Letter L-009 of 1674-04-24 to Constantijn Huygens about his further observations about blood, bones, teeth, and salt
June 1, 1674 Wrote Letter L-011 of 1674-06-01 to Henry Oldenburg about movement of liquid in capillary tubes, structure of body parts, growth of skin, and the size of red blood cells
July 6, 1674 Wrote Letter L-012 of 1674-07-06 to Henry Oldenburg bout sweat, hair, fat, tears, and improved capillary tubes
September 7, 1674 Wrote Letter L-014 of 1674-09-07 to Henry Oldenburg, stating that he will send further observations
September 7, 1674 Wrote Letter L-015 of 1674-09-07 to Henry Oldenburg about the anatomy of the eye and optic nerve of a cow, minerals eg. salt, clay, English and Flemish earth; first mention of protozoa in stagnant water
October 19, 1674 Wrote Letter L-016 of 1674-10-19 to Henry Oldenburg about eggs in the bile of cow, sheep, rabbits and poultry, the structure of metals, skin, and the bladder, and theories about the sense of taste.
December 4, 1674 Wrote Letter L-018 of 1674-12-04 to Henry Oldenburg about optic nerves and sight; enclosed specimen of cow's optic nerve
December 26, 1674 Wrote Letter L-019 of 1674-12-26 to Constantijn Huygens, enclosing a drawing of the optic nerve and excerpts from two recent letters
January 22, 1675 Wrote Letter L-021 of 1675-01-22 to Henry Oldenburg about a new technique for observing blood and sectioned brain tissue; optic nerve, smoke, gunpowder, and scorpions
February 11, 1675 Wrote Letter L-022 of 1675-02-11 to Henry Oldenburg about crystals, vinegar, soap, spices, cod, louse, and oak leaf.
March 26, 1675 Wrote Letter L-024 of 1675-03-26 to Henry Oldenburg about meals, seeds, and pearls; transparency; movement of fluids in plants and animals
August 14, 1675 Wrote Letter L-026 of 1675-08-14 to Henry Oldenburg about blood, taste of saps, sugar, and salt, and the mechanics of taste and digestion
December 20, 1675 Wrote Letter L-028 of 1675-12-20 to Henry Oldenburg about various omissions in previous letters, small animals in water, his theory of “globules”, and the aerometer he devised
January 1, 1676 Wrote Letter L-029 of some time in 1676 to Theodore Craanen about gold and mercury
January 22, 1676 Wrote Letter L-031 of 1676-01-22 to Henry Oldenburg about forwarding his mail and about sending his observations of little animals in water
February 22, 1676 Wrote Letter L-034 of 1676-02-22 to Henry Oldenburg about hair, cow skin, horn, and bone, inviting Hooke's response
April 21, 1676 Wrote Letter L-035 of 1676-04-21 to Henry Oldenburg about movement of liquid in ash and other trees, little animals in wine, and cinnamon and taste
May 29, 1676 Wrote Letter L-037 of 1676-05-29 to Henry Oldenburg about disagreements with Grew about the structure of wood and a further account of the vessels, fibres, and medullary rays of wood
July 28, 1676 Wrote Letter L-038 of 1676-07-28 to Henry Oldenburg; now lost
July 28, 1676 Wrote Letter L-039 of 1676-07-28 to Robert Boyle about the effects of air on ammonia and copper
October 9, 1676 Wrote Letter L-040 of 1676-10-09 to Henry Oldenburg about little animals in various waters and spice infusions, the relationship of their shape to taste, and whether there were little animals in the air
October 30, 1676 Wrote Letter L-043 of 1676-10-30 to Henry Oldenburg about his discussions with Grew and Boyle as well as the unreliability of the postal system
November 7, 1676 Wrote Letter L-045 of 1676-11-07 to Constantijn Huygens summarizing the observations of little animals in Letter L-040
November 27, 1676 Wrote Letter L-047 of 1676-11-27 to Henry Oldenburg, now lost
January 1, 1677 Wrote Letter L-049 of some time in 1677 to Robert Boyle, now lost
February 15, 1677 Wrote Letter L-051 of 1677-02-15 to Christiaan Huygens to thank him for translating a letter into French
March 23, 1677 Wrote Letter L-054 of 1677-03-23 to Henry Oldenburg about the quantity of little creatures in one drop of water
May 14, 1677 Wrote Letter L-056 of 1677-05-14 to Henry Oldenburg about muscles, blood, the movement of fluids in fruit, moxa, and cotton
October 5, 1677 Wrote Letter L-058 of 1677-10-05 to Henry Oldenburg about skin, eels, fleas, and measuring and counting the little animals; enclosed testimonials
October 16, 1677 Wrote Letter L-059 of 1677-10-16 to William Brouncker; he is sending some observations and a Latin translation
November 9, 1677 Wrote Letter L-060 of 1677-11-09 to William Brouncker about sperm and their movements in fresh human semen
December 2, 1677 Wrote Letter L-061 of 1677-12-02 to William Brouncker; now lost
January 1, 1678 Wrote Letter L-064 of some time in 1678 to Robert Boyle; now lost
January 14, 1678 Wrote Letter L-067 of 1678-01-14 to Robert Hooke about human blood, blood transfusions, flea larvae, and little animals in pepper water
February 14, 1678 Wrote Letter L-069 to Joseph Williamson, as Grew had requested
March 18, 1678 Wrote Letter L-070 of 1678-03-18 to Nehemiah Grew about sperm in other animals and what Harvey and de Graaf got wrong about reproduction
May 31, 1678 Wrote Letter L-073 of 1678-05-31 to Nehemiah Grew about teeth, bone, hair, and sperm and what de Graaf got wrong about ovulation
September 27, 1678 Wrote Letter L-074 of 1678-09-27 to Nehemiah Grew about sweat and globules in saliva and blood
December 26, 1678 Wrote Letter L-077 of 1678-12-26 to Constantijn Huygens about how son Christiaan's observations of little animals correspond to his own
February 21, 1679 Wrote Letter L-078 of 1679-02-21 to Nehemiah Grew about cod sperm and about not finding any little animals in blood or saliva
April 25, 1679 Wrote Letter L-080 of 1679-04-25 to Nehemiah Grew about living little animals in fish, hare, and dogs and his calculation that more than ten times as many living animals come from the milt of a cod as there are people living on the Earth
April 27, 1679 Wrote Letter L-081 of 1679-04-27 to Constantijn Huygens about the number of sperm in the milt of the cod
May 11, 1679 Wrote Letter L-083 of 1679-05-11 to Lambert van Velthuysen about people with gout
May 15, 1679 Wrote Letter L-084 of 1679-05-15 to Christiaan Huygens to explain more about his observations of little animals
May 20, 1679 Wrote Letter L-085 of 1679-05-20 to Constantijn Huygens about the number and size of the little animals he was observing
June 13, 1679 Wrote Letter L-087 of 1679-06-13 to Nehemiah Grew asking him to acknowledge two letters from earlier that year
June 13, 1679 Wrote Letter L-088 of 1679-06-13 to Lambert van Velthuysen about the origin of life and the lack of appreciation by physicians and surgeons
July 11, 1679 Wrote Letter L-090 of 1679-07-11 to Lambert van Velthuysen about about the chalk produced by gouty patients and about bladder stones
October 13, 1679 Wrote Letter L-092 of 1679-10-13 to Robert Hooke to inquire of Hooke why he had not received any correspondence from the Royal Society for months, also discussed bladder stones
November 14, 1679 Wrote Letter L-095 of 1679-11-14 to Lambert van Velthuysen about gout, salt, and drinking tea
November 20, 1679 Wrote Letter L-096 of 1679-11-20 to Robert Hooke, copying his Letter L-095 of 14 November 1679 about gout, salt, and drinking tea
January 12, 1680 Wrote Letter L-097 of 1680-01-12 to Robert Hooke about the structure of wood and sperm in fish
January 16, 1680 Wrote Letter L-098 of 1680-01-16 to Robert Hooke, enclosing a copy of Letter L-085 of 1679-05-20 to Constantijn Huygens about the number and size of little animals
February 13, 1680 Wrote Letter L-100 of 1680-02-13 to Robert Hooke that being elected a member of the Royal Society would be an honour
April 5, 1680 Wrote Letter L-102 of 1680-04-05 to Robert Hooke about the testicles and sperm of a rat and organisms in the gills of oysters and in the sap of vines
May 13, 1680 Wrote Letter L-104 of 1680-05-13 to Members of the Royal Society expressing his surprise and gratitude at being elected a member
May 13, 1680 Wrote Letter L-105 of 1680-05-13 to Robert Hooke to gratefully accept his election as a foreign member of the Royal Society and to acknowledge the receipt of his diploma
May 13, 1680 Wrote Letter L-106 of 1680-05-13 to Thomas Gale about little animals in sap and whether little animals are in the air
June 14, 1680 Wrote Letter L-107 of 1680-06-14 to Robert Hooke, a short cover letter
June 14, 1680 Wrote Letter L-108 of 1680-06-14 to Thomas Gale about beer, yeast, crab's eyes in vinegar, and little animals reproducing in hermetically-sealed tubes
August 9, 1680 Wrote Letter L-109 of 1680-08-09 to Robert Hooke to ask whether the Royal Society received previous letters and to promise further investigations into the formation of blood
September 28, 1680 Wrote Letter L-110 of 1680-09-28 to Thomas Gale to inquire whether Letter 107 of 1680-06-14 had arrived
November 12, 1680 Wrote Letter L-111 of 1680-11-12 to Robert Hooke about blood globules, lees of wine, globules in rain water, milk vessels, reproduction, little animals in the male seed of animals, and their incomprehensible smallness
November 4, 1681 Wrote Letter L-114 of 1681-11-04 to Robert Hooke about hog bristles, shedding hair, blackheads; living little animals in excrement, horse urine, clay, and gout
March 3, 1682 Wrote Letter L-116 of 1682-03-03 to Robert Hooke about muscle fibres, hair, the cell nucleus in the erythrocytes of fishes, the liver of salmons, beards of oysters, and the structure and growth of oyster shell
April 4, 1682 Wrote Letter L-119 of 1682-04-04 to Robert Hooke about the structure of the muscle tissue of lobsters and shrimps.
July 28, 1682 Wrote Letter L-120 of 1682-07-28 to Robert Hooke, now lost, asking whether figures of the anatomy of wood in Letter L-097 of 12 January 1680 will be published in print
January 1, 1683 Wrote Letter L-121 of some time in 1683 to an unknown "Sir"
January 22, 1683 Wrote Letter L-122 of 1683-01-22 to Christopher Wren about the function of the ovary, muscles of insects, drinking tea and mild beer, erythrocytes, and a theory on the formation of blood
March 9, 1683 Wrote Letter L-124 of 1683-03-09 to Francis Aston promising to send observations about generation and colors
May 20, 1683 Wrote Letter L-126 of 1683-05-20 to Anthonie Heinsius about generation and about the circulation of the blood, which he intends to communicate in a letter to the Royal Society
July 16, 1683 Wrote Letter L-128 of 1683-07-16 to Christopher Wren about the procreation of frogs, sperm in fowl's egg, reproduction of rabbits, little animals in frog intestines, a theory about digestion in humans and fish, and blood
July 22, 1683 Wrote Letter L-129 of 1683-07-22 to Anthonie Heinsius about Heinsius's reactions to an earlier letter
September 2, 1683 Wrote Letter L-132 of 1683-09-02 to Anthonie Heinsius, requesting his opinion of observations in Letter L-128
September 16, 1683 Wrote Letter L-134 of 1683-09-16 to Anthonie Heinsius about whether Heinsius would like a copy of his speculations on the living organisms in mouths and on the structure of the skin
September 17, 1683 Wrote Letter L-135 of 1683-09-17 to Francis Aston about saliva, nasal hairs and blackheads, skin, pores, calluses, and cleaning teeth; the discovery of bacteria in tartar
September 30, 1683 Wrote Letter L-136 of 1683-09-30 to Anthonie Heinsius, a note accompanying a copy of Letter L-135
October 1, 1683 Wrote Letter L-137 of October 1683 to Melchisedec Thévenot with some observations
October 14, 1683 Wrote Letter L-141 of 1683-10-14 to Anthonie Heinsius in reply to his recent Letter L-139
October 26, 1683 Wrote Letter L-143 of 1683-10-26 to Francis Aston in reply to Letter L-140 about egg yolks
December 28, 1683 Wrote Letter L-144 of 1683-12-28 to Francis Aston about human skin and its diseases, the intestines, the effects of vinegar, the intestinal wall and peristalsis, and an experiment to demonstrate the adsorption of food nutrients in the intestines.
April 14, 1684 Wrote Letter L-147 of 1684-04-14 to Francis Aston about lenses and corneas, the function of eye-lids, the involuntariness of blinking, the optic nerve, and the skin of Moors
July 25, 1684 Wrote Letter L-150 of 1684-07-25 to Members of the Royal Society about parts of the brain of several animals, chalk stones of gout, leprosy, and the scales of eels
January 5, 1685 Wrote Letter L-152 of 1685-01-05 to Members of the Royal Society about salts in wine and vinegar and in the stomach, the eye, the need for food and water, Descartes's theory on smallest water particles, and a theory of taste - salt, sour and sweet
January 23, 1685 Wrote Letter L-154 of 1685-01-23 to Members of the Royal Society about salts and their crystals and his theory about the causes of taste
March 30, 1685 Wrote Letter L-157 of 1685-03-30 to Members of the Royal Society about sperm, the uterus of a bitch, sheep embryos, ovaries in young animals and apples, and his claims that sperm are the life-carriers and that there are male and female sperm
July 13, 1685 Wrote Letter L-159 of 1685-07-13 to members of the Royal Society about reproduction of trees, transfer of nutrients, male and female trees, hazelnut, comparing reproduction of mammals with reproduction of plants, cross-breeding, and germination
August 10, 1685 Wrote Letter L-162 of 1685-08-10 to Anthonie Heinsius about cochineal
September 21, 1685 Wrote Letter L-164 of 1685-09-21 to Anthonie Heinsius about cochineal
October 12, 1685 Wrote Letter L-166 of 1685-10-12 to members of the Royal Society about the beginning of plants in seeds; chyle, sweat, about skin, optic nerve, and bile of fish; salts in beer vinegar and lemon juice; and spirits mixed with blood and wine vinegar
January 22, 1686 Wrote Letter L-168 of 1686-01-22 to members of the Royal Society about cinnabar naturalis, gunpowder, saltpeter, and air made by gunpowder and crab's eyes
April 2, 1686 Wrote Letter L-173 of 1686-04-02 to members of the Royal Society about the structure of bone, the bark of trees, skin and scales, the moisture evaporating from his body, and a little peeling piece of skin
April 14, 1686 Wrote letter L-174 of 1686-04-14 to Antonio Magliabechi, now lost
May 14, 1686 Wrote Letter L-175 of 1686-05-14 to members of the Royal Society about gall-nuts found on oak trees and the germination of plants
June 10, 1686 Wrote Letter L-177 of 1686-06-10 to members of the Royal Society about seeds of cotton, kapok, Bupariti, and coconuts, the reproduction of shrimp and lobster, and the eggs of shell fish
July 10, 1686 Wrote Letter L-178 of 1686-07-10 to members of the Royal Society about the growth and durability of wood felled in different seasons and countries, the annual growth rings, and how wooden barrels can be made watertight
September 10, 1686 Wrote Letter L-180 of 1686-09-10 to Daniël Papenbroek, a cover letter for Letter L-181
September 10, 1686 Wrote Letter L-181 of 1686-09-10 to Antonio Magliabechi, a cover letter for a copy of one of his books
October 30, 1686 Wrote Letter L-182 of 1686-10-30 to Antonio Magliabechi, a cover letter for copies of two of his books
March 1, 1687 Wrote Letter L-185 of 1687-03-01 to James II, King of England, as the dedication for one of his volumes
April 4, 1687 Wrote Letter L-186 of 1687-04-04 to the members of the Royal Society about the structure of the teeth of elephants, pigs, humans, oxen, and horses and about toothache
May 9, 1687 Wrote Letter L-187 of 1687-05-09 to members of the Royal Society about the structure of 'stone' of the medlar and the coffee bean and acid in plants
June 13, 1687 Wrote Letter L-188 of 1687-06-13 to members of the Royal Society about wheat and the seeds from a variety of plants
July 11, 1687 Wrote Letter L-189 of 1687-07-11 to members of the Royal Society about eggs of silkworms and caterpillars and humans' squinting and a theory for its cause
August 6, 1687 Wrote Letter L-190 of 1687-08-06 to members of the Royal Society about the calander and the louse and against spontaneous generation
August 6, 1687 Wrote Letter L-191 of 1687-08-06 to Robert Boyle about his recent letters
September 9, 1687 Wrote Letter L-192 of 1687-09-09 to members of the Royal Society about ant eggs, larvae and its development, feeding, sting, cocoon and nest
October 17, 1687 Wrote Letter L-193 of 1687-10-17 to members of the Royal Society about amber, 'burned paper' from the sky, rotifers, maggots, blow flies, the stinging hairs of nettles, and the East-Indian centipede
November 28, 1687 Wrote Letter L-194 of 1687-11-28 to members of the Royal Society about his discovery that cochineal was an insect and his experiments with cinchona bark
January 1, 1688 Wrote Letter L-195 of sometime in 1688 to Robert Boyle, now lost
May 25, 1688 Wrote Letter L-196 of 1688-05-25 to members of the Royal Society about a medicinal root and bladderstones
July 6, 1688 Wrote Letter L-197 of 1688-07-06 to the members of the Royal Society bezoar stone, monkey stone, gout tubercles, and red coral and white coral
August 3, 1688 Wrote Letter L-198 of 1688-08-03 to the members of the Royal Society about plaster, alabaster, gypsum, Muscovite glass, cobblestone, shell lime, masonry mortar, lime, cement, sand stone, and slate
August 24, 1688 Wrote Letter L-199 of 1688-08-24 to the members of the Royal Society about gnats, horseflies; growth of branches, germination of wheat plants, the soft and hard roe of cod, and the number of sperm in a cod's soft roe
September 7, 1688 Wrote Letter L-200 of 1688-09-07 to the members of the Royal Society about development of the eggs of green frogs, blood circulation in frogs and the tail fin of roach and bream, and the shape of red blood cells
September 23, 1688 Wrote Letter L-201 of 1688-09-23 to Melchisedec Thevenot, a cover letter for a copy of Leeuwenhoek's Letter L-200, published separately as Den waaragtigen omloop des bloeds.
January 1, 1689 Wrote Letter L-202 of sometime in 1689 to Antonio Magliabechi, a cover letter for one of his books
January 12, 1689 Wrote Letter L-203 of 1689-01-12 to Robert Boyle, a cover letter for Continuatio epistolarum and a copy of Letter L-204
January 12, 1689 Wrote Letter L-204 of 1689-01-12 to the members of the Royal Society about his observation of the circulation of the blood in a variety of fish as well as a description of the construction of his ‘eel spy-glass’ and the slime on the skin of an eel
April 1, 1689 Wrote Letter L-206 of 1689-04-01 to the members of the Royal Society
October 1, 1689 Wrote Letter L-207 of October 1689 to Christiaan Huygens about sending books to father Constantijn Huygens in London
September 18, 1691 Wrote Letter L-210 of 1691-09-18 to Antonio Magliabechi about
November 27, 1691 Wrote Letter L-212 of 1691-11-27 to the members of the Royal Society about blood, chyle, and an experiment to discover the volume of water when it is cold and when it is heated
January 4, 1692 Wrote Letter L-213 of 1692-01-04 to the members of the Royal Society about bladder and kidney stones and a chalk-like substance from a gout stone
February 1, 1692 Wrote Letter L-214 of 1692-02-01 to the members of the Royal Society about various peppers and their taste, tea and its effects of tea on digestion, and Spanish fly
March 7, 1692 Wrote Letter L-216 of 1692-03-07 to the members of the Royal Society about corn-weevels, corn-moths, caterpillars, butterflies, calanders, lice in corn-lofts, little animals in rain water, black-flies in blossoms, and maggots in cheese
April 22, 1692 Wrote Letter L-217 of 1692-04-22 to Richard Waller about the construction of an air pump and experiments with different liquids, seeds and small stones in urine, a hog's hair in the skin of a child, and grains of wheat
June 24, 1692 Wrote Letter L-218 of 1692-06-24 to the members of the Royal Society about more experiments with his air-pump, the structure of and blood in an insect's wing, a grey owlet moth, and the wing of a very small fly
August 12, 1692 Wrote Letter L-220 of 1692-08-12 to the members of the Royal Society about the shaft of a bird's feather as used in a quill, the lens and cornea of the human and calf eyes, 'wood-pipes' in different species of wood, bulrushes, and pine and lime wood
September 16, 1692 Wrote Letter L-221 of 1692-09-16 to the members of the Royal Society about little animals in dental tartar, theories of eel reproduction, worms in eel intestines, and blood vessels in grasshoppers
September 23, 1692 Wrote Letter L-222 of 1692-09-23 to Mary, Queen of Great Britain, the dedication to Derde Vervolg der Brieven
July 1, 1693 Wrote Letter L-225 of 1693-07-01 to Richard Waller, cover letter for a volume in Latin and confirmation of receipt of Letter L-224
October 15, 1693 Wrote Letter L-228 of 1693-10-15 to the members of the Royal Society about colors and the life cycle of fleas
October 27, 1693 Wrote Letter L-229 of 1693-10-27 to Pieter Rabus about procreation of the flea, the leather-jacket, and the mite
December 8, 1693 Wrote Letter L-230 of 1693-12-08 to Richard Waller, a cover letter
December 20, 1693 Wrote Letter L-231 of 1693-12-20 to the members of the Royal Society about spiders, lice, and mites
January 19, 1694 Wrote Letter L-232 of 1694-01-19 to Richard Waller as a cover letter for Letter L-231
January 24, 1694 Wrote Letter L-233 of 1694-01-24 to the members of the Royal Society about tapeworms and salt and sand in cod intestines
February 12, 1694 Wrote Letter L-235 of 1694-02-12 to Richard Waller as a cover letter for Letter L-233
February 24, 1694 Wrote Letter L-236 of 1694-02-24 to the members of the Royal Society about his experiments with solid phosphorus
March 2, 1694 Wrote Letter L-239 of 1694-03-02 to the members of the Royal Society about ear wax and hair, body hair, the amount of sweat secreted from the human body, and the possibility that sperm might penetrate the ovum
March 19, 1694 Wrote Letter L-240 of 1694-03-19 to the members of the Royal Society refuting George Garden's ideas in Letter L-227 about the role of the ovary and eggs
April 2, 1694 Wrote Letter L-241 of 1694-04-02 to the members of the Royal Society about the tongue of an ox and a pig and the heart of a sheep, ox, duck, chicken and cod
April 30, 1694 Wrote Letter L-242 of 1694-04-30 to the members of the Royal Society about his criticisms of Buonanni's theory of spontaneous generation, about mussels, barnacles, shrimp larvae, the eye of a dragon-fly, gnat, fly, and ant, and about ant eggs
May 26, 1694 Wrote Letter L-244 of 1694-05-26 to Richard Waller, cover letter for copy of Vierde Vervolg der Brieven
September 14, 1694 Wrote Letter L-245 of 1694-09-14 to Richard Waller about blood circulation and having sent six copies of his portrait to London
November 30, 1694 Wrote Letter L-246 of 1694-11-30 to Pieter Rabus about about dragon-fly eyes and eggs, crab eyes, vertebrate corneas, another rejection of spontaneous generation, and the impregnation of women
April 10, 1695 Wrote Letter L-247 of 1695-04-10 to Anthonie Heinsius about blood and its circulation in a crab's leg, crystals in evaporated crab blood, and the hairs on a crab's leg
April 22, 1695 Wrote Letter L-248 of 1695-04-22 to Frederik Adriaan van Reede about the apple-blossom weevil, its larvae, their danger, and their metamorphosis and the reproduction of black flies on apple tree blossoms
May 1, 1695 Wrote Letter L-251 of 1695-05-01 to Anthonie Heinsius about weevils, nutmegs and their safe storage, and tobacco seeds and their germination
May 18, 1695 Wrote Letter L-253 of 1695-05-18 to Frederik Adriaan van Reede about the apple-blossom weevil, caterpillars and the metamorphosis of the small ermine moth, and parasitic flies
May 21, 1695 Wrote Letter L-254 of 1695-05-21 to Pieter Rabus about the eggs and blood vessels of the ray
May 23, 1695 Wrote Letter L-255 of 1695-05-23 to Maarten Etienne van Velden about the impossibility of small flies being generated from the body of a big dead caterpillars, again refuting the theory of spontaneous generation
July 10, 1695 Wrote Letter L-260 of 1695-07-10 to Frederik Adriaan van Reede about aphids, their reproduction, and the unsuccessful search for male aphids
July 12, 1695 Wrote Letter L-261 of 1695-07-12 to Maarten Etienne van Velden about the metamorphosis of caterpillars and of parasitic larvae coming out of a dead caterpillar
July 20, 1695 Wrote Letter L-262 of 1695-07-20 to Anthonie Heinsius about about scales from his own skin, wool threads from his stockings, salt from his sweat, and air bubbles and salt crystals from his ear wax
July 21, 1695 Wrote Letter L-263 of 1695-07-21 to Pieter Rabus about the report that a large caterpillar emerged from a woman's ear and fumigation with sulphur to remove it; Leeuwenhoek cannot find any mites in his own auditory canal
August 15, 1695 Wrote Letter L-264 of 1695-08-15 to Frederik Adriaan van Reede about oysters and their larvae, repudiating spontaneous generation
August 15, 1695 Wrote Letter L-265 of 1695-08-15 to Antonio Magliabechi, the dedication of Arcana Naturae Detecta
August 16, 1695 Wrote Letter L-266 of 1695-08-16 to inform Antonio Magliabechi that he has dedicated Arcana Naturae Detecta to him; he mentions the visit of the Elector Palatine
August 18, 1695 Wrote Letter L-267 of 1695-08-18 to Anthonie Heinsius about detonating gunpowder in a closed glass bulb and measuring the increase in volume after the explosion; in a partial vacuum, glass bulbs may implode
August 20, 1695 Wrote Letter L-268 of 1695-08-20 to Frederik Adriaan van Reede about again about oysters and their sperm and aphids and other parasites
September 10, 1695 Wrote Letter L-270 of 1695-09-10 to Pieter Rabus about his attempt to breed maggots with his own ear-wax as food and a movement in his ear due to the vibration of a little hair against the ear-drum
September 18, 1695 Wrote Letter L-271 of 1695-09-18 to Johann Wilhelm von Pfalz-Neuburg about swan mussel sperm, eggs, embryos, and locomotion, small animals as food for larger ones and oysters and their larvae; he again refutes spontaneous generation
October 18, 1695 Wrote Letter L-274 of 1695-10-18 to Antonio Magliabechi to accompany a parcel of books, which Leeuwenhoek gave to Baron Bettino Riasoli for delivery
October 31, 1695 Wrote Letter L-276 of 1695-10-31 to Magliabechi to acknowledge the receipt of Magliabechi's Letter L-272, to report on the books he sent and on his recent Letter L-271 to Johann Wilhelm von Pfalz-Neuburg
October 31, 1695 Wrote Letter L-277 of 1695-10-31 to Jacob Calckberner to request that he forward a package of books to Magliabechi
November 3, 1695 Wrote Letter L-279 of 1695-11-03 to Johann Wilhelm von Pfalz-Neuburg about larvae from swan mussels, little animals in water taken out of swan mussels, and extracts from letters to Oldenburg and Brouncker about the quantity of little animals
December 1, 1695 Wrote Letter L-281 of 1695-12-01 to Frederik Adriaan van Reede, the dedication of the Fifth Continuation of the Letters (Vijfde Vervolg der Brieven)
December 22, 1695 Wrote Letter L-282 of 1695-12-22 to acknowledge the receipt of two letters by Magliabechi and to tell him once again that the books have been forwarded to him
December 28, 1695 Wrote Letter L-283 of 1695-12-28 to Hendrik van Bleyswijk about herring, their stomach worms, the food in herring stomachs, and how small fish like herring catch food
February 20, 1696 Wrote Letter L-285 of 1696-02-20 to Frederik Adriaan van Reede about the anatomy of the body louse, especially the sexual organs and the louse's rapid reproduction, and his opposition to Jonston's and Kircher's observations on lice
March 8, 1696 Wrote Letter L-287 of 1696-03-08 to Nicolaas Witsen about white mace caused by vermin, a moth from a larva taken from mace, larvae and wings of the merchant grain beetle, and nutmeg; warehouses should be painted to protect spices from vermin
June 1, 1696 Wrote Letter L-289 of 1696-06-01 to Pieter Rabus about dowsing rods and the hazel branches used to make them, iron, and loadstone
July 6, 1696 Wrote Letter L-292 of 1696-07-06 to Nicolaas Witsen about his analysis of the mineral that Witsen sent with Letter L-291, ant stings, and lacquer particles on a tree that originate from the tree itself, not from ants
July 10, 1696 Wrote Letter L-294 of 1696-07-10 to Nicolaas Witsen about demonstrating the rotation of the earth with the aid of a glass globe filled with water in which wax particles are floating.
July 10, 1696 Wrote Letter L-295 of 1696-07-10 to the members of the Royal Society about the circulation of blood in eels; mites, figs, strawberries, and a lobster's leg; a transcription of Christiaan Huygens's Letter L-223 about the reproduction of eels
July 16, 1696 Wrote Letter L-296 of 1696-07-16 to Frederik Adriaan van Reede about the male and female sexual organs of oysters and their larvae
July 23, 1696 Wrote Letter L-297 of 1696-07-23 to Pieter Rabus honey-dew on lime-trees; moisture from vine tendrils leads to a theory on the production of lacquer in tropical trees; his Delft friend has lost the capacity to handle the dowsing-rod
August 26, 1696 Wrote Letter L-300 of 1696-08-26 to Frederik Adriaan van Reede about plant-lice, its embryos and parasitization, black flies and their caterpillars on apple-trees, and English oysters from Zierikzee
August 28, 1696 Wrote Letter L-301 of 1696-08-28 to Antonio Magliabechi to acknowledge receipt of Letter L-293, to inquire about the reaction of the grand duke to his work, and to thank Magliabechi for sending printed matter and book news from Italy
August 29, 1696 Wrote Letter L-302 of 1696-08-29 to Hendrik van Bleyswijk about oak-wood containing beetle larvae, which appeared to be able to feed on wood, and the cause of the differences in quality of oak-wood
September 7, 1696 Wrote Letter L-303 of 1696-09-07 to thank Magliabechi for Letter L-290 of 5 June and Letter L-293 of 8 July 1696 and to request that Magliabechi spare him exaggerated praise henceforth
September 12, 1696 Wrote Letter L-304 of 1696-09-12 to Anthonie Heinsius about rennet and curd, chalk and crab's-eyes in vinegar, smoking tobacco to cure toothache, the gall-bladder and omasum of a calf, milk-clotting, and his contradiction of a physician
September 27, 1696 Wrote Letter L-305 of 1696-09-27 to Hendrik van Bleyswijk about the age of fishes, especially herring, using scales and the structure of greater weever's spine and the painfulness of its sting
October 26, 1696 Wrote Letter L-306 of 1696-10-26 to Maarten Etienne van Velden to accompany a presentation copy of his printed letters, Sesde Vervolg Der Brieven (Sixth Continuation of the Letters)
October 30, 1696 Wrote Letter L-307 of 1696-10-30 to a "gentleman in Brabant", a cover letter accompanying a copy of Sesde Vervolg der Brieven
November 15, 1696 Wrote Letter L-309 of "latter part" of 1696 to Harmen van Zoelen about what I had learned from an East India Trader
February 12, 1697 Wrote Letter L-314 of 1697-02-12 to Maarten Etienne van Velden, regretting Van Velden's difficulties caused by his defence of Copernicus and in support, enclosing a copy of a letter from a gentleman in Brabant
February 19, 1697 Wrote Letter L-315 of 1697-02-19 to Hans Sloane about sending Sesde Vervolg der Brieven and wanting to receive the latest Philosophical Transactions and the works of Malpighi
March 25, 1697 Wrote Letter L-316 of 1697-03-25 to the members of the Royal Society as a cover letter to Continuatio Arcanorum Naturae
April 5, 1697 Wrote Letter L-318 of 1697-04-05 to the members of the Royal Society about experiments with magnets, a meniscus in a glass, and patients given 'sympathetic' powder as a medicine by a German quack doctor
May 15, 1697 Wrote Letter L-320 of May 1697 to Victor van Beughem about how to distribute the enclosed copies of Continuatio Arcanorum Naturae
June 6, 1697 Wrote Letter L-323 of 1697-06-06 to Antonio Magliabechi about marine fossils found in mountain rocks and the present of copies of Continuatio Arcanorum Naturae sent to Florence
July 1, 1697 Wrote Letter L-324 of 1697-07-01 to Luca Giamberti to request that he send Magliabechi's gift book by a freighter from Cologne via Düsseldorf to Dordrecht
September 3, 1697 Wrote Letter L-328 of 1697-09-03 to Jan van Leeuwen about ears of wheat with smut and a theory of fungous disease in grain; refutes the notion that honey-dew causes smut ears
September 10, 1697 Wrote Letter L-329 of 1697-09-10 to the members of the Royal Society about small white eggs mixed with earth, a pulsating pulmonary vein in an egg, Roman snails, the rootlets of a wheat grain, one of his own teeth, and young oysters
November 2, 1697 Wrote Letter L-330 of 1697-11-02 to Antonio Magliabechi to thank him for two of his letters and to complain that the book sent to him has not yet arrived
January 1, 1698 Wrote Letter L-331 of sometime between late December 1697 and mid-January to Johan Arnoldi about the book that Magliabechi had sent
January 19, 1698 Wrote Letter L-334 of 1698-01-19 to Govert Bidloo about how little animals get into the human body through canal water and food preparation
February 10, 1698 Wrote Letter L-335 in February 1698 to Johan Arnoldi that he should do whatever it takes to get the book that Magliabechi sent and that he will reimburse whatever it costs
February 20, 1698 Wrote Letter L-336 of 1698-02-20 to Antonio Magliabechi about problems during the transport of the book that Magliabechi had sent to Leeuwenhoek as a present
April 1, 1698 Wrote Letter L-340 to Johan Arnoldi that he will reimburse him for his expenses in getting the book
April 15, 1698 Wrote Letter L-341 around April 1698 to Harmen van Zoelen about using plaster to whitewash wooden storage containers to prevent damage from worms
April 17, 1698 Wrote Letter L-342 of 1698-04-17 to Antonio Magliabechi that the book had at last arrived and received a place of honour in his house
May 9, 1698 Wrote Letter L-343 of 1698-05-09 to the members of the Royal Society about the compound eye of a beetle and the number of facets, the human cornea, drone flies, and gnat brains and leg muscles
August 14, 1698 Wrote Letter L-346 of 1698-08-14 to Antonio Magliabechi about payment for and arrival of a book sent by Magliabechi as a present as well as an enclosed catalogue of an art collection of the Mennonite minister A. van Beusecom
September 20, 1698 Wrote Letter L-347 of 1698-09-20 to Anthonie Heinsius about blood circulation in an eel's tail, the transition of arterial into venous capillaries, and the connection between the thickness of the wall of the blood vessels and the viscosity of the blood
December 17, 1698 Wrote Letter L-349 of 1698-12-17 to Harmen van Zoelen to defend himself against Hartsoeker's claim to have been the first to discover sperm
February 1, 1699 Wrote Letter L-352 of 1699-02-01 to a "right honorable sir" about his inspection of a mineral containing gold and silver from the Salida mine in Sumatra; his theory about the formation of gold and silver ores
February 15, 1699 Wrote Letter L-353 of February 1699 to Johan Arnoldi about how he can repay Leeuwenhoek
February 28, 1699 Wrote Letter L-354 of 1699-02-28 to Antonio Magliabechi about reimbursement for Arnoldi's expenses for the book that Leeuwenhoek finally received
April 26, 1699 Wrote Letter L-355 of 1699-04-26 to Harmen van Zoelen about the damage caused to mace by insects and their larvae, damage to bamboo, and the biting and stinging of noxious white ants and the struggle against them by chalking of wood
June 9, 1699 Wrote Letter L-356 of 1699-06-09 to the members of the Royal Society to dispute Dalenpatius's 'Nouvelles de la Republique des lettres', in which sperm are described as having the shape of the human body
June 23, 1699 Wrote Letter L-357 of 1699-06-23 to the members of the Royal Society in response to Martin Lister's objections against his theory of generation; his opposition to the theory of spontaneous generation; the assumption of male and female spermatozoa
August 5, 1699 Wrote Letter L-358 of 1699-08-05 to the directors of the United East India Company in Delft about circulation of the blood in the leg of a scorpion from India that they had sent to him; a description of the eight eyes and the pincers
September 25, 1699 Wrote Letter L-360 of 1699-09-25 to Hans Sloane to request a reaction to previously sent letters and as cover letter for Letter L-361 of the same day to the Royal Society
September 25, 1699 Wrote Letter L-361 of 1699-09-25 to the members of the Royal Society about the circulation of blood in tadpole capillaries, the transition from arteries to veins, blood clotting, the dissolution of clotted blood, and the origin of the name thunder-pad
October 1, 1699 Wrote Letter L-362 of sometime in October 1699 to Ehrenfried von Tschirnhaus about medicines, his aversion to bleeding and purging, and his preference for tea and coffee as medicine; credulity of people who trust impostors and poorly trained physicians
October 16, 1699 Wrote Letter L-363 of 1699-10-16 to Antonio Magliabechi about tiny animalcules from ditchwater, his opposition to spontaneous generation, and how animals serve as food for each other
January 2, 1700 Wrote Letter L-364 of 1700-01-02 to Hans Sloane about liver fluke, gnat larvae, circulation of blood in a frog, and little animals in its feces
January 14, 1700 Wrote Letter L-365 of 1700-01-14 to Nicolaes Boogaert van Belois about blood circulation in lizard legs, the way a lizard and a scorpion react to one another, the scorpion's eyes, pincers, and sting and the muscle fibres in that sting
May 20, 1700 Wrote Letter L-366 of 1700-05-20 to Hendrik van Bleyswijk about the eyes and the sting of a centipede and the reactions of a fly and a lizard to a centipede
May 20, 1700 Wrote Letter L-367 of 1700-05-20 to Anthonie Heinsius about peat, its composition and origin, how much soil washed into the sea by rivers and effect on sea level compared to amount of soil lost through peat cutting
June 2, 1700 Wrote Letter L-368 of 1700-06-02 to Frederik Adriaan van Reede about the eyes, mouth parts, food, intestines, and eggs of a shrimp
June 14, 1700 Wrote Letter L-370 of 1700-06-14 to answer Hans Sloane's Letter L-369 that he has examined the sperm of many animals, but if there is any animal that the Royal Society would like him to investigate, he will do so.
June 16, 1700 Wrote Letter L-371 of 1700-06-16 to a "Highly Learned Sir" summarizing his earlier investigations of bees, especially the queen bee and her eggs, and of the propagation of other insects
July 9, 1700 Wrote Letter L-372 of 1700-07-09 to Hans Sloane about red blood cells in flounder and salmon, how their oval form changes shape to pass through capillaries, and the sperm of a young cock
July 10, 1700 Wrote Letter L-373 of 1700-07-10 to Anthonie Heinsius about seeds of plants and parts of invertebrates in peat found near Hellevoetsluis
July 27, 1700 Wrote Letter L-375 of 1700-07-27 to Hans Sloane about experiments with the larvae of cheese flies received from Sloane a week earlier and the treatment of his wife's toothache with vitriol
August 1, 1700 Wrote Letter L-376 of 1700-08-01 to "Your Most Serene Highness" about the influence of atmospheric pressure on the level of a water column in a glass tube during a capillary rise; comparison to the column of mercury in a barometer
September 7, 1700 Wrote Letter L-377 of 1700-09-07 to Hans Sloane to follow up on Letter L-375 to Sloane about fly larvae in cheese
October 26, 1700 Wrote Letter L-378 of 1700-10-26 to Hans Sloane about black flies on fruit trees, aphids, comparing the parthenogenetic procreation of aphids with sperm, and the development of the pupae of moths
December 25, 1700 Wrote Letter L-380 of 1700-12-25 to Hans Sloane about the sperm of a ram and his objections to Nicolaas Hartsoeker's claim to have discovered sperm first in 1678 when Leeuwenhoek had written to the Royal Society about sperm in 1677
January 28, 1701 Wrote Letter L-382 of 1701-01-28 to Hans Sloane about gall on a willow and more about larvae from cheese
February 9, 1701 Wrote Letter L-383 of 1701-02-09 to Frederik Adriaan van Reede about pores in willow wood and advice for the improvement of peat
April 8, 1701 Wrote Letter L-384 of 1701-04-08 to the mayors of Delft about his calculation of the difference between the coal measures of Delft and Rotterdam and how to calculate the volume of a pyramid
April 15, 1701 Wrote Letter L-385 of 1701-04-15 to the members of the Royal Society about sperm from cod, a calculation of its size, and ram and pike sperm
June 21, 1701 Wrote Letter L-389 of 1701-06-21 to John Chamberlayne about salt crystals in rain-water and notches in a sharpened knife
June 21, 1701 Wrote Letter L-390 of 1701-06-21 to the members of the Royal Society about spiders, their blood, their silk thread and its structure, their sting, and laying their eggs
June 21, 1701 Wrote Letter L-391 of 1701-06-21 to Hans Sloane about the claimed qualtity of other people's magnifying glasses, injuries to the cornea, and the impossibility of observing the smallest particles of matter
August 2, 1701 Wrote Letter L-392 of 1701-08-02 to the members of the Royal Society about circulation of blood in young eels and announcing his bequest of 26 magnifying glasses
August 26, 1701 Wrote Letter L-393 of 1701-08-26 to Frederik Adriaan van Reede about measuring the fall of water, an accurate instrument for such measurements, and his invention of a level
December 6, 1701 Wrote Letter L-397 of 1701-12-06 to Hans Sloane as a cover letter for Letter L-398 to John Somers
December 6, 1701 Wrote Letter L-398 of 1701-12-06 to John Somers about the sperm of young cocks living for days outside the cock and whether that was long enough to fertilise a hen's egg
December 20, 1701 Wrote Letter L-399 of 1701-12-20 to the members of the Royal Society about the sperm of spiders and how they copulate
February 9, 1702 Wrote Letter L-400 of 1702-02-09 to Hendrik van Bleyswijk about three types of little animals from the gutter of his house, one of which was eaten by a larger animal, which could revive after being dried out
February 14, 1702 Wrote Letter L-401 of 1702-02-14 to the members of the Royal Society about balsam, an apparatus he designed to inhale smoke and vapour, blood vessels in sheep lungs, his own phlegm, and the theory that cold air harms lungs
April 20, 1702 Wrote Letter L-403 of 1702-04-20 to Karl von Hessen-Kassel as a cover letter for Letter L-404
April 20, 1702 Wrote Letter L-404 of 1702-04-20 to Karl von Hessen-Kassel about silkworms, the structure of the silk thread, and the organs that produce it, eyes, pincers, blood vessels, and cocoons, sperm from an adult silk moth, and the scales on its wings
April 28, 1702 Wrote Letter L-405 of 1702-04-28 to the members of the Royal Society about little animals and air bubbles in rain water and the circulation of blood in an eel
December 8, 1702 Wrote Letter L-407 of 1702-12-08 to John Chamberlayne about cleaning and preserving teeth by polishing them with salt and ash of tobacco and whether tea and coffee harm teeth; requested a book on Peruvian silver mines
December 25, 1702 Wrote Letter L-408 of 1702-12-25 to the members of the Royal Society about duckweed, its roots and reproduction, the little animals attached to it, and asexual reproduction
February 5, 1703 Wrote Letter L-409 of 1703-02-05 to the members of the Royal Society about colony-forming little animals from Delft canal water, dissolving silver and gold in acids, and why there is little duckweed on the surface of water in cold weather
February 26, 1703 Wrote Letter L-410 of 1703-02-26 to the members of the Royal Society about the structure and germination of pips of oranges from Surinam and Curaçao
November 3, 1703 Wrote Letter L-412 of 1703-11-03 to Hans Sloane to thank him for sending recent numbers of Philosophical Transactions and the book on Peruvian silver mines, also as a cover letter for Letter L-413
November 3, 1703 Wrote Letter L-413 of 1703-11-03 to the members of the Royal Society about the liver fluke in soil from meadows, worms and other little animals in soil, and a theory about how they propogate
December 4, 1703 Wrote Letter L-414 of 1703-12-04 to the members of the Royal Society about the shape of a grain of fine sand from the Dutch East Indies
January 8, 1704 Wrote Letter L-415 of 1704-01-08 to the members of the Royal Society about salt crystals out of rainwater that during a "frightful storm" in December had dashed against the windows of his house
February 1, 1704 Wrote Letter L-416 of 1704-02-01 to the members of the Royal Society about red sandstone from the cathedral at Utrecht compared to diamond, his theory about the origin of diamonds, and marble, Bentheim stone, alabaster, and gold and silver ore
February 11, 1704 Wrote Letter L-418 of 1704-02-11 to Pieter Valckenier about rock crystal, its origins in the mountains, and fossils of ocean fish found in his Swiss mountains
February 15, 1704 Wrote Letter L-419 of mid-February 1704 to Siewert Centen to refute his contention that cochineal must be a plant, not an animal
March 21, 1704 Wrote Letter L-422 of 1704-03-21 to the members of the Royal Society about cochineal and the insects that are the source of this dye
July 22, 1704 Wrote Letter L-423 of 1704-07-22 to the members of the Royal Society about muscle fibers of whales, the structure of the eyes' lenses of whales and cod, and his theory about why fish have no eyelids
September 1, 1704 Wrote Letter L-424 of sometime before 16 September 1704 to Pieter Hotton about the canals that raise the yellow sap in a common plant
September 16, 1704 Wrote Letter L-426 of 1704-09-16 to the members of the Royal Society about leaves of aloe and a plant called dragon's blood sent to him by Pieter Hotton with Letter L-425
October 3, 1704 Wrote Letter L-427 of 1704-10-03 to John Chamberlayne as a follow-up to Letter L-407 about tobbacco ashes, the salt crystals obtained from them, and an oily substance obtained by heating the ashes of tobacco
November 4, 1704 Wrote Letter L-428 of 1704-11-04 to the members of the Royal Society about little animals with two wheels, found on duckweed, how they move, their parasites, and the theory that sea water makes land more fertile
December 13, 1704 Wrote Letter L-431 of 1704-12-13 to the members of the Royal Society about the origin of rock-crystal and a description and analysis of fossils of sea animals and two Roman dice all found in Switzerland and given to him by Pieter Valkenier
March 3, 1705 Wrote Letter L-433 of 1705-03-03 to the members of the Royal Society about silver deposits on his own hands after he mixed gold and silver with acid and treatment of a callous on his own finger with vitriol and then acid
March 3, 1705 Wrote Letter L-434 of 1705-03-03 to John Chamberlayne about vitrified matter from a haystack that had caught fire, sent to Leeuwenhoek with Letter L-429
March 12, 1705 Wrote Letter L-436 of 1705-03-12 to Antonio Magliabechi about precipitating silver from aqua fortis, silver sulphate crystals, their comparison with rock crystal, saltpetre, and sugar candy
March 27, 1705 Wrote Letter L-437 of 1705-03-27 to the members of the Royal Society about his theory that bark tissue is formed from wood; cross-sections and pictures of vessels and cells of bark and wood tissue of cherry, birch, cinnamon, and lime trees and from cork
April 24, 1705 Wrote Letter L-438 of 1705-04-24 to the members of the Royal Society about a fern and its seed capsules and an experiment to open and close them
May 25, 1705 Wrote Letter L-439 of 1705-05-25 to the members of the Royal Society about crystals from various minerals that Pieter Valkenier left after his recent visit and experiments to dissolve and recrystallize them
December 18, 1705 Wrote Letter L-441 of 1705-12-18 to Francesco Corner about the structure of a pearl compared to that of an oyster's shell, salts from pearls and oysters' shells heated and afterwards dissolved, and an argument against the grit of pearls as medicine
December 29, 1705 Wrote Letter L-442 of 1705-12-29 to the members of the Royal Society about pumice stone, its origins, and its salts, sponge and a theory about how it absorbs water, and coral
March 7, 1706 Wrote Letter L-444 of 1706-03-07 to Govert Bidloo to follow up on his visit earlier that day about what Leeuwenhoek discovered in the intestines they had viewed
March 19, 1706 Wrote Letter L-446 of 1706-03-19 to the members of the Royal Society about an East Indian tree and mixing his own blood with the crushed seed of the tree and water, the effects of a drink made from hemp seed, and a dissected hemp seed
April 20, 1706 Wrote Letter L-447 of 1706-04-20 to the members of the Royal Society about a piece of hanged woman's intestinal wall brought to him by Govert Bidloo
June 1, 1706 Wrote Letter L-448 of 1706-06-01 to the members of the Royal Society about the structure of a sheep's spleen and a flea's organ for stinging and sucking
January 1, 1707 Wrote Letter L-449 of 1707-01-01 to Angelus van Wikhuysen about the use of cinchona bark as a remedy
May 17, 1707 Wrote Letter L-452 of 1707-05-17 to John Chamberlayne to complain that his four most recent letters to the Society had not been answered; about a bezoar stone and the visit of Corner; offered to send a copy of Letter L-436 to Magliabechi
July 5, 1707 Wrote Letter L-454 of 1707-07-05 to the members of the Royal Society to acknowledge the receipt of Letter L-453 and to cover the enclosed copy of Letter L-436 of 12 March 1705 to Magliabechi
July 12, 1707 Wrote Letter L-455 of 1707-07-12 to the members of the Royal Society as thanks for numbers of Philosophical Transactions and as cover to a copy of Letter L-441 to Corner; mentioned the visit of Gilbert Burnet
July 25, 1707 Wrote Letter L-457 of 1707-07-25 to the members of the Royal Society about cinchona bark and using it as a treatment for fever
August 10, 1707 Wrote Letter L-458 of 1707-08-10 to Anthonie Heinsius as a cover letter for a copy of Letter L-457 of 25 July 1707 to the Royal Society
October 18, 1707 Wrote Letter L-459 of 1707-10-18 to the members of the Royal Society about the fur on his own tongue after an attack of fever, the fur of a thrush patient, and a theory about the origin of tongue fur
November 22, 1707 Wrote Letter L-461 of 1707-11-22 to the members of the Royal Society about a hairy substance, received with Letter L-460, supposedly excreted by a woman suffering from a kidney infection
December 6, 1707 Wrote Letter L-462 of 1707-12-06 to the members of the Royal Society about the tongue of an ox, its skin and papillae, and the tongue of a pig with its papillae and muscle fibres
January 1, 1708 Wrote Letter L-463 of 1708-01-01 to the members of the Royal Society about the composition of red coral, the effects when heated and when dissolved in aqua fortis and boiling rain water, and crystals in dissolved coral
June 29, 1708 Wrote Letter L-464 of 1708-06-29 to the members of the Royal Society about his further observations of the white furry substance on his own tongue during attacks of fever
August 28, 1708 Wrote Letter L-467 of 1708-08-28 to the members of the Royal Society about how an eel's heart and the valves in the vien of its tail work; his own pulse and pulsation of the heart of an eel and a pike
October 9, 1708 Wrote Letter L-468 of 1708-10-09 to the members of the Royal Society about the mucous membrane in the palate and in the nose of a cow and about its tongue
September 10, 1709 Wrote Letter L-470 of 1709-09-10 to Hans Sloane, a cover letter for the following Letter L-471 to John Chamberlayne.
September 10, 1709 Wrote Letter L-471 of 1709-09-10 to John Chamberlayne about the cutting edge of a razor and its nicks as well as its setting and maintenance
November 22, 1709 Wrote Letter L-472 of 1709-11-22 to John Chamberlayne about human beard hairs and muscle fibres of a cod, both cut off with a razor
January 14, 1710 Wrote Letter L-474 of 1710-01-14 to the members of the Royal Society about Alexander Stuart's visit, blood circulation in eels, crystallisation of sugar, minerals from Hungary, and his new fish viewer for visitors to see blood circulating in an eel's tail
February 2, 1710 Wrote Letter L-475 of 1710-02-21 to the members of the Royal Society about the shape and crystallization of diamonds
June 6, 1710 Wrote Letter L-476 of 1710-06-06 to the members of the Royal Society about silver dissolved in aqua fortis
November 11, 1710 Wrote Letter L-477 of 1710-11-11 to the members of the Royal Society about what happened when he dissolved gold dust from Guinea in aqua regia
August 15, 1711 Wrote Letter L-479 of 1711-08-15 to Anthonie Heinsius as a cover letter for Philosophical Transactions, vol. 26, no. 319, with Leeuwenhoek's article on the pulse and copies of notes on gold from Guinea and hailstones
August 18, 1711 Wrote Letter L-480 of 1711-08-18 to James Petiver about the sperm of young rams and to explain what happened when Petiver tried to visited
September 22, 1711 Wrote Letter L-481 of 1711-09-22 to the members of the Royal Society about mites, their reproduction, eggs, larvae, a calculation of the size of a mite egg, the hair of a honey-bee, and metamorphis of larvae from dried fish into a full-grown animal
November 23, 1711 Wrote Letter L-482 of 1711-11-23 to Anthonie Heinsius about claims by Fryer and Kircher supporting spontaneous generation, which Leeuwenhoek rejected; gold, copper, and silver dissolved in aqua fortis and the separation of gold and copper
December 29, 1711 Wrote Letter L-483 of 1711-12-29 to Anthonie Heinsius, a cover letter for Letter L-484, naming the author of the article in Philosophical Transactions that he criticizes but does not name in the following letter, meant for publication
December 29, 1711 Wrote Letter L-484 of 1711-12-29 to Anthonie Heinsius to refute an article in Philosophical Transactions; he calculates the quantity of blood propelled by each heartbeat and estimates how often the total blood volume circulates through the body
March 1, 1712 Wrote Letter L-485 of 1712-03-01 to the members of the Royal Society about the skin and flesh of a whale, its seminal vessels, and its blood with comparisons to the blood of other fish
April 12, 1712 Wrote Letter L-486 of 1712-04-12 to the members of the Royal Society about the structure of the genetalia of a female elephant and the structure of an elephant's skin
June 10, 1712 Wrote Letter L-487 of 1712-06-10 to the members of the Royal Society about little animals on a mussel's shell, the ciliar motion of the gills, and the intestines and ovaries of mussels
November 8, 1712 Wrote Letter L-488 of 1712-11-08 to Anthonie Heinsius, a cover letter for Letter L-489
November 8, 1712 Wrote Letter L-489 of 1712-11-08 to Anthonie Heinsius about the muscle fibres of a whale
December 17, 1712 Wrote Letter L-490 of 1712-12-17 to Anthonie Heinsius about salts in the blood of a shrimp and the muscle fibres and enveloping membranes of cod, shrimp, flounder, and perch
January 1, 1713 Wrote Letter L-491 of a few years before 1713 to Jan Meerman how barley is filling, but provides little nourishment, also about a membrane in the barley
February 28, 1713 Wrote Letter L-492 of 1713-02-28 to Jan Meerman about wheat and barley grains, beans, peas, and chestnuts, vessels and membranes in coconut rind, and the embryo in an apple pip and in a coconut
March 14, 1713 Wrote Letter L-493 of 1713-03-14 to Jan Meerman about the eye of a whale, the lens, and the cornea and calculations of the pressure on a whale's eye at great depth
March 25, 1713 Wrote Letter L-494 of 1713-03-25 to Adriaen van Assendelft about little hairs of a mouse, mole, cat, and rabbit all have the same shape; thick, dark bear hair, composition and color of hair, hair of deer and elk
March 29, 1713 Wrote Letter L-495 of 1713-03-29 to Anthonie Heinsius about the muscles of cows, muscle fibers of mice thinner than whales, fat particles, muscle fibers of sheep same size as of mice and oxen, though the animals differ greatly in size
June 28, 1713 Wrote Letter L-496 of 1713-06-28 to the members of the Royal Society about little animals on duckweed, muscle fiber membranes, and a list of unanswered letters; little animals in his mouth come from rinsing glasses with pond water
June 30, 1713 Wrote Letter L-497 of 1713-06-30 to Anthonie Heinsius about the composition of crabs’ eyes and lobster and crab shells, ring-shaped structures in lobster pincer shell, compared to annual rings of woody vegetation, and the lobster's muscle fiber membrane
October 12, 1713 Wrote Letter L-499 of 1713-10-12 to Hans Sloane as a cover letter for a copy of Letter L-489 on muscle fibres of a whale and a request for new numbers of Philosophical Transactions and a list of fellows of the Society to be sent to relatives in Rotterdam
October 24, 1713 Wrote Letter L-501 of 1713-10-24 to Antony Cinck refuting, as requested, Kircher's ideas about poisonous little animals on sage leaves and spontaneous generation
June 22, 1714 Wrote Letter L-504 of 1714-06-22 to the members of the Royal Society to acknowledge Letter L-503 and numbers of Philosophical Transactions and to query why figures of the muscle fibres of whales were not published
August 21, 1714 Wrote Letter L-507 of 1714-08-21 to the members of the Royal Society about the muscle fibres of cow, chicken, mouse, honeybee, flea, ant, and whale and the blood vessels in the leg of a fly; thanks for recent numbers of Philosophical Transactions
October 26, 1714 Wrote Letter L-509 of 1714-10-26 to the members of the Royal Society about muscle fibres and enclosing membranes in the legs of a mosquito, rose chafer, fly, crane fly, honeybee and cow; rectifying earlier opinion, the contractions in a muscle are spiral
November 4, 1714 Wrote Letter L-510 of 1714-11-04 to Adriaen van Assendelft, comparison between muscle fibres and a tightened rope; the shorter the rope, the quicker it can shrink; application of this comparison on the size of muscle fibres of a cow and of a mouse
November 9, 1714 Wrote Letter L-511 of 1714-11-09 to Isaac Newton, now lost, to cover Letter L-512
November 9, 1714 Wrote Letter L-512 of 1714-11-09 to the members of the Royal Society about the muscles of an ox, sheep, chicken, mouse, and hare
November 20, 1714 Wrote Letter L-513 of 1714-11-20 to the members of the Royal Society about muscle fibres and tendons from a mouse leg, a duck wing, a honeybee, a polecat leg, and between the ribs of a mouse; a theory about the structure and action of tendons
January 11, 1715 Wrote Letter L-514 of 1715-01-11 to Anthonie Heinsius, a cover letter for a copy of a recent letter on muscle fibres
March 26, 1715 Wrote Letter L-516 of 1715-03-26 to Antony Cinck about the structure and action of muscle fibres and tendons from the leg of a mouse and the head of cod and a wire model of spiral contraction
July 7, 1715 Wrote Letter L-518 of 1715-07-07 to Antony Cinck about contracting and stretching of muscle fibres and tendons; their connection in lobster and crab; no observed nerves between muscle fibres and membranes; cannot confirm that nerves are hollow
August 1, 1715 Wrote Letter L-519, now lost, of sometime before August 1715 to Gottfried Leibniz about his observations and recent letters
September 28, 1715 Wrote Letter L-521 of 1715-09-28 to Gottfried Leibniz about scholars who do not agree with Leeuwenhoek; sperm the same size in different animals; the pulse; posthumous letters; muscle fibers, tendons, and nerves; Hartsoeker; why he won't train students
November 18, 1715 Wrote Letter L-523 of 1715-11-18 to Gottfried Leibniz, a cover letter for Letter L-524
November 18, 1715 Wrote Letter L-524 of 1715-11-18 to Gottfried Leibniz about vessels in the flesh of fruit and in the seeds of various strains of pears, a pear's embryo and the structure of a pear's skin, and spiral vessels in tea-leaves
January 1, 1716 Wrote Letter L-525 of some years before 1716 to Frederik Adriaan van Reede about the large number of eggs in the roe of a ling
February 25, 1716 Wrote Letter L-526 of 1716-02-25 to Anthonie Heinsius as a cover letter to "notes" about tendons, muscle fibres, and starch grains
March 3, 1716 Wrote Letter L-527 of 1716-03-13 to Gottfried Leibniz about human twins, trees, birds, size of sperm, number of eggs in fishes' hard roe, structure of tendons and muscle fibres, the heart; does not want to be paid for research or to teach students
May 10, 1716 Wrote Letter L-530 of 1716-05-10 to Hubert Kornelis Poot to thank him for two published panegyrics; the size and origin of little animals; wonder at the smallness of little animals and the largeness of the universe; periwinkle seeds
May 16, 1716 Wrote Letter L-531 of 1716-05-16 to Gerard van Loon about hops from Liege, the structure of hops, its bitter oil, and salt particles from the oil, a comparison with sugar candy, and hop embryos; Leeuwenhoek descended from a family of beer brewers
May 19, 1716 Wrote Letter L-532 of 1716-05-19 to Gottfried Leibniz about muscle and tendon fibers, mammal teats, sperm; did not find eggs in ovaries, Fallopian tube, or womb; cannot imagine how the Fallopian tube could suck sperm; does not know the ovary's function
May 22, 1716 Wrote Letter L-533 of 1716-05-22 to Cornelis Spiering about the scales of a carp that Spiering sent him, using scales to age a fish, eggs in hard roe and sperm in soft roe food for other fishes, shrimp eggs, and the life span of whales and fish
June 12, 1716 Wrote Letter L-536 of 1716-06-12 to thank professors Cink, Narez, and Rega for the honorary medal; barley germination and nutrients; again rejects spontaneous generation
June 22, 1716 Wrote Letter L-537 of 1716-06-22 to Jan Gerard Kerkherdere about how wheat, barley, beans, peas, rice, buckwheat, and maize become food for animals and discusses Leeuwenhoek's techniques for preparing samples
September 17, 1716 Wrote Letter L-538 of 1716-09-17 to Abraham Cornelis van Bleyswyck about his own intestinal ailment and the roles of chyle, gall (bile), and the diaphragm in the digestive process
September 28, 1716 Wrote Letter L-540 of 1716-09-28 to Herman Boerhaave about how trees grow and withstand wind; coconut palm wood and nut; he acknowledges previous errors in his observations of coconut tree trunks
November 5, 1716 Wrote Letter L-544 of 1716-11-05 to Herman Boerhaave about the size of sperm from rams, cod, and ling, little animals from rain water and soil, and blood in arteries and veins
November 17, 1716 Wrote Letter L-545 of 1716-11-17 to Gottfried Leibniz about reproduction, numbers of sperm and seeds, reproductive organs of sheep and ram, fallopian tube too small to let eggs through
November 21, 1716 Wrote Letter L-546 of 1716-11-21 to Herman Boerhaave about ram sperm and details of his experimental methods
March 2, 1717 Wrote Letter L-547 of 1717-03-02 to Abraham van Bleyswyck about the structure of nerves and the associated fat in the spinal cords of cows and sheep
March 6, 1717 Wrote Letter L-548 of 1717-03-06 to the members of the Royal Society tendons and muscle fibres in sheep, flea, ox, honeybee, oyster, and mussel
March 6, 1717 Wrote Letter L-549 of 1717-03-06 to the members of the Royal Society about pig brains, apples, and coconuts; blood circulation nourishes; new technique to examine brains; tea and coffee keep the blood thin
May 6, 1717 Wrote Letter L-550 of 1717-05-06 to Ewout van Bleiswijk about dragonflies' muscle fibres, compound eyes, and corneal facets, flies, lobster, and crab
May 26, 1717 Wrote Letter L-551 of 1717-05-26 to Abraham van Bleyswyck about the structure of nerves and associated blood vessels and membranes, the structure of the spinal cord and brains of a pig, cow, and mouse, and the nerves of a calf, bream, and lamb
June 15, 1717 Wrote Letter L-552 of 1717-06-15 to the members of the Royal Society about the muscle fibres of an ox and a flea and the reproduction of fleas
July 6, 1717 Wrote Letter L-553 of 1717-07-06 to Antony Cink about how two doctors treated his recent illnesses with saltpeter and opium; saltpeter’s effects on the blood and its efficacy as a drug
July 13, 1717 Wrote Letter L-554 of 1717-07-13 to Jan Gerard Kerkherdere about one of his personal ailments, the consequences for the digestion of eating fatty meat, the particles in his own excrement, and the role of chyle and gall during digestion
August 18, 1717 Wrote Letter L-556 of 1717-08-19 to Adriaan Swalmius about membranes inside an eggshell, salt crystals from an eggshell, and how birds and oysters produce shells
August 26, 1717 Wrote Letter L-557 of 1717-08-26 to Herman Boerhaave, following up on Letter L-546, about a ram's seed balls, vas deferens, and epididymis, millet grains or mustard seeds as units of measurement, sperm compared smaller little animals, and a sperm’s tail
September 10, 1717 Wrote Letter L-558 of 1717-09-10 to Frederik Adriaan van Reede about haddock intestines, roach and cod, and how scales determine the age of herring, perch, bream, and cod
September 17, 1717 Wrote Letter L-559 of 1717-09-17 to the members of the Royal Society about his own skin's fat globules and sweat ducts, holes in his finger nails, sweat ducts in humans and in cow teats, and how lice and fleas use sweat ducts to obtain their food
October 8, 1717 Wrote Letter L-560 of 1717-10-08 to the members of the Royal Society about Pareira Brava root and the effect of salt particles from it upon blood, starch grains from the membranes of the root, and the roots of “China” and “Irias"
October 22, 1717 Wrote Letter L-561 of 1717-10-22 to the members of the Royal Society about the brain of a cod, the nerves of cod and haddock, and the spinal cord of haddock
November 20, 1717 Wrote Letter L-562 of 1717-11-20 to the members of the Royal Society about tendons and nerves of sheep, lamb, cow, and ox; his last letter to the Royal Society; expresses his gratitude for being elected a fellow and for Philosophical Transactions
December 8, 1717 Wrote Letter L-563 of 1717-12-08 to Charles VI, Holy Roman emperor, as the dedication for Send-Brieven
November 28, 1718 Wrote Letter L-564 of 1718-11-28 to Francesco Corner, a cover letter for Epistolae Physiologicae
January 9, 1720 Wrote Letter L-565 of 1720-01-09 to the members of the Royal Society about muscle fibres and membranes of a cow, mites on the flesh of a whale, and the nerves around the muscle fibres and tendons of a cow
November 20, 1720 Wrote Letter L-566 of 1720-11-20 to the members of the Royal Society about bone membrane and the canals in bone, the cell layers and blood vessels in the bone membrane, and bone from the rib of a cow
January 15, 1721 Wrote Letter L-567 of 1721-01-15 to members of the Royal Society about the stomata of the leaves of boxwood, the number of them, and the down on the skin of a peach and a quince
January 24, 1721 Wrote Letter L-568 of 1721-01-24 to the members of the Royal Society about vessels in wood from Ambon (Indonesia), oakwood, and pinewood, the muscle fibres of a cow, a whale, and a mouse, and the structure of a red blood cell
April 11, 1721 Wrote Letter L-569 of 1721-04-11 to the members of the Royal Society about how flesh fibers are nourished by the blood vessels, this time in fish
June 27, 1721 Wrote Letter L-570 of 1721-06-27 to the members of the Royal Society about finally discovering the little holes in the membranes of beans and peas and about the little vessels in seed membranes
April 21, 1722 Wrote Letter L-572 of 1722-04-21 to the members of the Royal Society about the muscular fibres of different animals and whether iron becomes magnetic over time
May 1, 1722 Wrote Letter L-573 of 1722-05-01 to the members of the Royal Society about the structure of fat particles in sheep, lamb, flatfish, and perch
May 1, 1722 Wrote Letter L-574 of 1722-05-01 to James Jurin, a cover letter to Letter L-573, asking for support for his observations of hermaphroditic animals
June 13, 1722 Wrote Letter L-576 of 1722-06-13 to the members of the Royal Society about the reproductive organs of a ewe and a fetus from it
June 13, 1722 Wrote Letter L-577 of 1722-06-13 to James Jurin, a cover letter for Letter L-576, expressing doubts that inoculations protect against smallpox
July 7, 1722 Wrote Letter L-578 of 1722-07-07 to the members of the Royal Society about calluses on human skin
July 7, 1722 Wrote Letter L-579 of 1722-07-07 to James Jurin, a cover letter to Letter L-578, that no little animals are to be found in smallpox pustules; again opposes a proponent of spontaneous generation
November 20, 1722 Wrote Letter L-581 of 1722-11-20 to James Jurin about the miscroscopic structure of diamonds and rock crystal
March 19, 1723 Wrote Letter L-583 of 1723-03-19 to the members of the Royal Society about blood, now lost
March 19, 1723 Wrote Letter L-584 of 1723-03-19 to James Jurin about blood, the size of blood globules, the state of his health, and the role of the ovary in reproduction
May 31, 1723 Wrote Letter L-585 of 1723-05-31 to the members of the Royal Society about the structure and texture of the diaphragm, the source of his most severe ailment
August 1, 1723 Wrote Letter L-587 of sometime in August to James Jurin about the similarities between globules in blood and in the lees of wine to argue against Jurin’s hope to discover how blood globules are made
August 1, 1723 Wrote Letter L-588 of 1723-08-00 to James Jurin about his spermist view of the generation of animals and palpitations of his diaphragm, his final letter