Baer began (§ 1) with the formulation of the contem- 

 porary idea that "the embryo of the higher animals passes 

 through the permanent forms of the lower animals." He 

 underlined 



that the higher animals in single stages of 

 individual development, from the first origin 

 to completed development, respond to the 

 permanent forms of the animal series, and that 

 the development of individual animals follow 

 the same laws as that of the whole animal 

 series. Therefore, the more highly organized 

 animal in its individual development passes 

 through the most important permanent stages 

 lower than its own, so that the periodical 

 differences of the individual may be related to 

 the differences in the permanent animal forms. 

 (I Sch. V la, 286 - 287 (199)) 



The development of this idea Baer attributed to the 

 time when systematic investigations of early embrycgenesis 

 were absent, with the exception of the work of Malpighi 

 and Wolff. It was developed by Johann Friedrich Meckel, 

 Junior, whom Baer did not name and only mentioned as a 

 person who "acquired a highly serious knowledge about the 

 history of development of the higher organisms" (I Sch. 

 V la, 200) . Baer remarked next on those evolutionary 

 conclusions based on the similarity of embryos of higher 

 animals to the adult lower animals. Ridiculing these 

 hurried evolutionary conclusions, Baer caricatured the 

 transformation of fish into land vertebrates and the 

 elongation of the heron's neck as a result of its trying 

 to reach to catch fish. His objections were directed not 

 so much against the principle of evolution in general, or 

 even against Lamarck's principle cf inheritance of acquired 

 characteristics, as against "the permanent arrangement of 

 animal forms in one series" (I Sch. V la,b, 200). 



In section 2, therefore, Baer turned to his doubts and 

 objections to the repetition of the phylogenetic history in 

 ontogenesis. The comparative study of adult animal forms made him 

 sceptical of the idea of ontogeny following phylogeny. Insofar as 



349 



