Theories of Chemical Development 279 



mcnt to itself, which constitutes the great defect of all 

 theories of chemical development. 



This investigator believes that the chemical activity 

 of the cell is due in general to colloidal ferments which 

 are contained within them and of which each is destined 

 for a special chemical process. He admits thereby the 

 existence of numerous colloidal ferments in cells with 

 multiple chemical processes, and he sees in ontogeny the 

 result of a series of chemical reactions which follow one 

 another according to the principle of fructifying 

 causality : 



"During the development of the embryo there takes 

 place a chemical differentiation parallel with the morpho- 

 logical differentiation. The formation of new chemical 

 anlagen indicates the appearance of different ferments at 

 definite stages of embryonal development." "One could 

 hardly form a better idea of the chemical transformations 

 going on during the early development of the embryo 

 than by supposing that at first only a very small number 

 of ferments become active, and that these transform 

 existing material into new substance, among which pro- 

 ferments or ferments of another kind appear, through 

 which the first then become annihilated, and which 

 become supplanted in their turn by a new generation of 

 ferments which they have themselves produced and so on 

 until the cycle of new chemical formations requisite for 

 the history of the race is run through. The epigenesis of 

 form would be then only the expression of the epigenesis 

 of chemical forces." 211 



We shall pass over the fact that all these theories of 

 chemical development have yet to explain the connection 



J11 Hofmeister : La chimie de la cellule. Revue generate des 

 sciences; Aug. 15, 1902. P. 730731. 



