Wrote Letter L-143 of 1683-10-26 to Francis Aston in reply to Letter L-140 about egg yolks

October 26, 1683
Standard reference information
Collected Letters volume: 

No manuscript is known.

In this letter, Leeuwenhoek replied to Aston’s recent letter of about the cicatricula on the yolk of an egg.

A copy of this translation of Leeuwenhoek's reply to Aston’s Letter L-140 of 11 October 1683 is to be found in London, Royal Society, Letter Book Original 9.17, p. 31. It has no salutation or signature and is titled, “Mr. Leewenhoeck to Mr Aston being the Translation of his letter dated the 26th of October 1683, about the speck or point of the yolk of the egg virt Cicatricula.”

In L.’s previous letter to Aston, Letter 76 [39] L-135 of 17 September 1683, Collected Letters, vol. 4, he describes, among other observations about saliva and dental hygiene, his discovery of bacteria in dental plaque. Aston replied with Letter L-140 of 11 October 1683, in this volume, asking L. to investigate the cicatricula in chicken eggs.

I received yours of the first instant[1], whereby I understand that the Royal Society has not yet met since their last adjournment. When you have communicated my last observations, I desire you to let me know whether they were well accepted[2].

By the speck or point of the yolk of the egg, I mean the cicatricula[3], or mark which the yolk has, wherein Malpighi found the first rudiments of the chicken[4]. For as often as I sought the male seed in the yolk of the egg, I sought it only in the cicatricula, whether the eggs were now laid, or had been sat upon a day or two. The parts whereof the cicatricula consists, appeared to me so [ed: unclear word] and large, that I made no representation of them. I know well that the chicken is first fed out of the white, for if an egg be broken a day or two before the chicken is hatched, we find the yolk almost entire, which serves for nourishment afterwards. I have not viewed the Transactions you say you sent me last[5], and shall expect them thankfully as being very much obliged to you. I have some other observations written, which I would not burden you with at present, desiring you to present my service to the Royal Society.


[1] See Aston’s Letter L-140 of 11 October 1683, in this volume.

[2] At the beginning of the Royal Society’s meeting of 24 October 1683 O.S., L.’s Letter 96 [39] L-135 of 17 September was read and discussed in detail. See Letter L-140 of 11 October 1683, n. 2, in this volume, for the account of the meeting in Birch, The History of the Royal Society of London, vol. IV, p. 219.

[3] Cicatricula, the germinating or formative point in the yolk of an egg.

[4] Malpighi’s De Formatione Pulli in Ovo [The formation of chickens in eggs] was published by John Martyn for the Royal Society in 1673.

[5] For these numbers of Philosophical Transactions, see Letter L-125 of 27 March 1683 from Aston to L., n. 3, in this volume.