Le Dantec 273 
law of the repetition of phylogeny by ontogeny, as we 
have already had occasion to remark in connection with 
the similar hypotheses of Spencer, Hertwig and several 
others. This requires, as we have seen, the conception 
of the addition of a new substance to all those formerly 
present. 
All variations of the organism are ascribed by 
LeDantec, as we have already seen, to total or partial 
destruction of some of the different plastic substances 
(a), which make up the living substance, whereby their 
quantitative proportions become changed; but never to 
the formation of new plastic substances. Likewise dif- 
ferent species would differ from one another in the 
number and quality of the plastic substances (a). From 
this it follows: 1, that no further development can be 
effected by any given living matter, if the number of 
its substances has become very small, and thus an abso- 
lute inalterability must be established as soon as this 
number is reduced to one; 2, that the development of 
the species can have been produced only by successive 
total destructions of an always greater number of these 
plastic substances; 3, that the further a species is devel- 
oped, the smaller therefore must be the number of the 
plastic substances which form its respective living matter. 
One would thus arrive at the absurdity, that the simpler 
the living substance is the more complex must be the 
organisms formed from it. 
Finally LeDantec, like Spencer, Hertwig and the 
others is unable to explain histological differentiation by 
this supposed similarity of living substance in all parts 
of the organism: 
“A muscular element differs entirely from a nervous 
epithelial element, and these differences are manifested 
