Chap, i.] OF THE PROCESSES OF GKOWTH. 5l?5 



embiyological evolution, as well as for certain species of his- 

 tological elements, the partisans of spontaneous genesis, sup- 

 ported moreover by numerous and precise observations, affirm, 

 that for the most part in the animal kingdom, and here and 

 there in the vegetal kingdom, new histological elements appear 

 spontaneously in the intercellular blastemas. 



Even if we admit that the defenders of spontaneous genesis 

 have generalised a little too much the application of their doctrine, 

 it is certainly on their side that there is the largest amount of 

 truth. "We must, in any case, admit two grand processes of his- 

 tological generation : proliferation, or multiplication by extension 

 and division of substance and genesis, or multiplication by a sort 

 of living precipitation in the heart of the blastemas. The two 

 processes are observable in the two organic kingdoms, but in 

 very different degrees, each of these two great modes of his- 

 tological multiplication being dominant in the one kingdom 

 and exceptional in the other. In short, proliferation and genesis 

 are the rule, the first in the vegetal kingdom, the second in the 

 animal kingdom. 



