Nicolaas Hartsoeker

rival over the discovery of sperm
Birth or Baptism date: 
March 26, 1656
Death or Burial date: 
December 10, 1725

Hartsoeker's infant in spermHartsoeker, a Dutch lens grinder and natural philosopher, was the son of a Remonstrant minister. Beginning in his twenties, he became interested in optics and embryology.

In the 1682 portrait by Casper Netscher below, note in the bottom left of the portrait the conventional microscope similar to Hooke's that had two lenses in a tube. Note also the single-lens microscope just below in an ornate frame. Hartsoecker developed the screw-barrel microscope. He is best known for his ideas about the "l'enfant", infant (often given the alchemical term "homunculi", but not by Hartsoecker) in human sperm. The image on the right comes from page 230 of Essay de dioptrique.

Hartsoeker quarreled with, among others, Huygens, Newton, Leibniz, and Leeuwenhoek, who wrote to Leibniz in 1715 (Send-Brieven p. 170):

It has come to my ears that Hartsoeker hasn't much of a reputation among the learned; and when I saw that he laid claims to untruths, and was stuck up, I looked into his writings no further.

Leeuwenhoek was referring to Hartsoeker's book Proeve der deur-gesigt-kunde, the Dutch translation of Essai de dioptrique, which had been published in Paris in 1694. In it, Hartsoeker claimed to have discovered sperm. In December 1698, Leeuwenhoek wrote to Harman van Zoelen defending his own priority. He wrote of Hartzoeker with a withering put-down:

I do not know what kind of Person this Hartsoeker is, because there are more people who bear the name of Hartsoeker and have called at my House, amongst others, many Years ago, an Aged Man who, they told me, was a Minister of the Remonstrant Church at Rotterdam and who had with him a Son, who was a Young Student and who was repeatedly admonished by his Father to attend closely, because I was showing things, as the Minister said, which had never been revealed in the World.

It appears strange to me that Mr. Hartsoeker uses the words that, to his knowledge, he is the first of all who began to examine the sperm of Animals with the magnifying glasses.

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Hartsoeker returned the insult in the posthumously published (1730) Cours de physique accompagné de plusieurs pièces concernant la Physique qui ont dèja paru et d’un extrait critique des lettres de M. Leeuwenhoek.

Je n’ai jamais été surpris qu’un homme comme notre Auteur, don’t le genie étoit assurement au dessous du médiocre, ait parlé comme il a fait des globules du sang, du lait etc., mais mon étonnement a été bien grand de voir que de célébres Médecins et Professeurs en Philosophie et en Médecine, l’ont cité avec éloge sur sa belle découverte des pretendues boules, et ont adopté son galimatias. I had never been surprised that a man like our Author, whose genius is surely below mediocre, should speak of the globules of  blood and milk etc. as he did, but my shock was really great when I saw that famous doctors and professors of Philosophy and Medicine had cited him with praise because of his beautiful discovery of the supposed globules, and had adopted his gobbledygook (galimatias = meaningless speech).

Lindeboom discusses the dispute between Leeuwenhoek and Hartsoeker in his chapter on sexual reproduction, especially pages 140-144, in Antoni van Leeuwenhoek, 1632-1723: studies on the life and work of the Delft scientist commemorating the 350th anniversary of his birthday.