Theories of Chemical Development 279 
ment 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.” 2" 
We shall pass over the fact that all these theories of 
chemical development have yet to explain the connection 
11F1ofmeister: La chimie de la cellule. Revue générale des 
sciences; Aug. 15, 1902. P. 730—73I. 
