308 FROM THE GREEKS TO DARWIN 



so that from seeds on the one side and eggs on 

 the other came the many and diverse organisms. 

 Meckel more clearly anticipated von Baer in 

 1811, in the passage: "There is no good physiolo- 

 gist who has not been struck, incidentally, by the 

 observation that the original form of all organ- 

 isms is one and the same, and that out of this one 

 form, all, the lowest as well as the highest, are 

 developed in such a manner that the latter pass 

 through the permanent forms of the former as 

 transitory stages." 



Von Baer, in 1834, in a lecture entitled "The 

 Most General Laws of Nature in all Develop- 

 ment," maintained that "only in a very childish 

 view of nature could organic species be regarded 

 as permanent and unchangeable types, and that 

 in fact they can be only passing series of genera- 

 tions, which have developed by transformation 

 from a common original form."^ 



Serres^ enlarged the arguments of Meckel and 

 showed that the missing links in the chain of 

 Evolution may all be discovered, if we seek them, 

 in the life of the embryo. When we compare ani- 

 mals that have arrived at their complete devel- 

 opment, we find many differences between them; 

 but if we compare them during their successive 

 stages of Evolution, we see that these differ- 



IHaeckel: The History of Creation, 1892, vol. I, p. 112. 

 2Pr4cis d'Anatomie Transcendante, 1842, p. 90. 



