of the plan of development." Baer continued, "the type can 

 be known best by its method of development.- This conveys 

 the difference in the existing relationship of the initially 

 agreeing germs" (Sch. V C4k, 257 - 258) . 



The given confirmation must be considered as recognitiion 

 of the initial unity and general origin of all the animal 

 world. Here Baer returned to the idea about a single method 

 of acquisition of independence for all animals, by formation 

 of the vesicle-shaped stage in which the most general charac- 

 ter is recognized. The unity of the original form, inherent 

 to each of the four types, has as a consequence the similarity 

 between the representatives of the different types, which are 

 preserved throughout life. Baer specifically said that the 

 initial similarity of the embryos of all animals does not 

 disappear absolutely in the adult form. 



In Baer's study of differences but also of similarities 

 in the types of development, one can perceive reflections of 

 Naturphilosophie. In distinction from the principles of 

 German Naturphilosophie, which originated almost completely 

 from a priori understandings, Baer's opinion depended on 

 thoroughly checked observations; therefore they stand in 

 close connection with the evolutionary ideas of the second 

 half of the nineteenth century. 



From the assertion that the type of animal depends on 

 that form of development which is inherent to its type, 

 Baer concluded that a rational classification of animals 

 should be based on embryological data. This idea he illus- 

 trated by examples. That the insects are organized higher 

 than the arachnids and Crustacea, and that amphibia and 

 reptiles are considered differentiated from each other by 

 classes can only be established by studying the history of 

 their development. 



The last, sixth scholium briefly sums up the others. 

 In the process of multiplication, a part becomes a whole, 

 and in the process of development the independence of the 

 organism from its surrounding medium increases. The 

 definition of its form also increases; internally, from the 

 most general parts, the most specific develop and their 

 originality becomes more distinct. All these conclusions 



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