SECT. 3] AND EIGHTEENTH CENTURIES 215 



The otherwise unknown physician d'Aumont, who wrote the 

 article on "Generation" in Diderot's famous Encyclopaedia, brought 

 this out in an interesting way, for himself an ovist, he summarised 

 the arguments, which, in 1757, were destroying the animalculist 

 position, and reducing rapidly the number of its adherents. 



1. Nature would never be so prolific as to produce such millions 

 of spermatic animalcules, each one with its soul, unnecessarily. 



2. The spermatic animalcules of all animals are the same size, no 

 matter how large the animal is: how, therefore, can they be 

 involved in its generation? 



3. They are never found in the uterus after coitus, but only in 

 the sperm (?). 



4. How do they reproduce their kind? 



5. What evidence is there that they are any different from the 

 animalcules (of similar shape, etc.) which are to be found in 

 hay infusion, scrapings from the teeth, etc. ? Nobody supposes 

 that these have any relation to reproduction. 



3-14. The Close of the Eighteenth Century 



The last forty years of the century were not marked by any great 

 movement in a fruitful direction for morphological embryology, an 

 iconographic wave of some merit due to Albinus, W. Hunter, Tarin, 

 Senffj Rosenmuller, Danz and Soemmering excepted ; and it was not 

 until 181 2 that J. F. Meckel the younger translated Wolff's papers 

 into German. This was one of the principal influences upon Pander 

 and von Baer. In his introduction, Meckel describes how Wolff's 

 work had been disregarded, and points out that Oken, writing in 

 1806, had apparently never even heard of it. In the very early 

 years of the nineteenth century morphological embryology received 

 a great impetus, however. One of the most interesting figures of 

 the new period was de Lezerec, a Breton, whose father had been 

 in the Russian naval service. The son, as a Russian naval cadet, no 

 doubt stimulated by the writings of Wolff, who had lived at St Peters- 

 burg, used to incubate eggs on board ship. He eventually left the 

 sea, studied medicine at Jena, and wrote an excellent dissertation 

 on the embryology of the chick in 1 808, which Stieda has recently 

 brought to light. He then went to Paris, and, taking a medical 

 appointment at Guadeloupe, was lost to science. Very much more 

 important was the work of Pander in 181 7 and von Baer in 1828, 



