240 Theories Treating of Inheritance 



in which it had arisen, and to suppose instead that when 

 once the idioplasm has been modified there remains in it 

 nothing more of the preceding states, not even in a latent 

 or potential condition. At least this would seem to be 

 indicated in the following passages. 



"The theory of biogenesis makes it necessary for us 

 to introduce into Haeckel's statement of the fundamental 

 biogenetic law, a few modifications and explanatory addi- 

 tions through which the contradiction (between this law 

 and this theory) may be avoided. We should drop the 

 expression: repetition of the forms of extinct ancestors, 

 and substitute for it: repetition of forms which obey the 

 laws of organic development and which progress from 

 the simple to the complex. We should lay the emphasis 

 upon this, that in embryonic forms, just as in the adult 

 forms of animals, are expressed general laws of develop- 

 ment of organized living substance." 



"The periodically repeated development of pluricellu- 

 lar individuals from unicellular representatives of the 

 species, or individual ontogeny, is brought about in general 

 accordance with the same rules as the preceding onto- 

 genies, but becomes each time a little modified correspond- 

 ing to the extent to which the characteristic cell of the 

 species was modified in phylogeny." 



"That certain conditions of form recur in the develop- 

 ment of animals with such great constancy, and in the 

 main in similar ways, is due chiefly to the fact that in all 

 circumstances they furnish the prerequisite conditions 

 under which the next later stages of ontogeny can be 

 produced." 



"The unicellular organism, on account of its very 

 nature, can be transformed into a pluricellular organism 



