ment of every organism begins with it. the primitive condi- 

 tion is in no way recapitulated from the time when, perhaps 

 only single-celled amoebas existed on our planet. For ac- 

 cording to our theory the egg-cell, for instance, of a now 

 extant mammal is no simple and indifferent, purposeless 

 structure, as it is often represented, (as according to 

 Haeckel's "biogenetic principle" it would necessarily be); 

 we see in it, in fact, the extraordinarily complex end- 

 product of a very long historic process of development, 

 through which the organic substance has passed since that 

 hypothetical epoch of single-celled organisms." 



"If the eggs of a mammal now differ very essentially 

 from those of a reptile and of an amphibian because in their 

 organization they represent the beginnings only of mam- 

 mals, even as these represent only the beginnings of rep- 

 tiles and amphibians, by how^ much more must they differ 

 from those hypothetical single-celled amoebas which could 

 as yet show no other characteristics than to reproduce 

 amoebas of their own kind." 



This is a view which has frequently been clearly ex- 

 pressed by anti-Darwinians: The egg-cells of the various 

 animals are in themselves fundamentally different and can 

 therefore have nothing in common but similarity of struc- 

 ture. In opposition to Hertwig, Haeckel in his superficial 

 way deduces from it an internal similarity as well. After a 

 few polite bows before his old teacher, Haeckel, Hertwig 

 thus summarizes his view: "Ontogenetic (that is, those 

 stages in the individual development) stages therefore give 



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