CHAP, in.] OF GROWTH IN THE ANIMAL KINGDOM. 289 



It would seem at the first glance as if the question of knowing 

 whether the anatomical elements arise by scission or by genesis 

 , belonged purely to the domain of science, and were dependent 

 solely on observation and e-xperiment. This however is by no 

 , means the case. This is one of the subjects which have the 

 j privilege of bringing into play passions by no means scientific. 

 , In effect, the spontaneous genesis of the anatomical elements in 

 . the blastemas seems to have a close connection with the theory 

 I of spontaneous generation, which by some is so much execrated 

 and mocked. But if we contemplate the matter with composure 

 all this fury seems to have very little justification. Two facts 

 . are very certain : the first, that anatomical elements multiply ; 

 iithe second, that they multiply by diverse processes, but in 

 ij general conditions which are identical. These principal facts 

 (dominate all others. Little it matters whether a cell arises by 

 I scission, by germination, by endogenesis, or by genesis. Defini- 

 tively the contents of an anatomical element do not differ 

 ; essentially from the environing blastema ; in both cases there are 

 )| organised substances, in the midst of which is effected the inces- 

 ; sant molecular movement which constitutes the fundamental 

 i! phenomenon of life. If assimilation prevails over disassimilation 

 there must necessarily result the formation of new living centres, 

 I of new anatomical elements, and from the philosophical point 

 of view it matters little whether this new formation is effected 

 I without or within a cell. 



Observation in effect shows that in the living tissues the 



I processes of scission and of genesis are sometimes associated, 



I and sometimes succeed each other. Nuclei, cells even, arising 



J from genesis, for instance leucocytes, can afterwards multiply by 



segmentation and germination. 1 



According to M. Robin the advent of epithelial layers on the 

 surface of the cutaneous dermis and the mucous membranes 



1 Ch. Robin, loc. cit., pp. 47, 48. 



