352 Fecundation 



phenomenon, be it only in so far as a phenomenon of 

 assimilation, is* itself essentially a rhythmic phenomenon. 



In regard to fecundation we know that it was Spencer 

 who first recognized what has been more or less explicitly 

 accepted by others, that it consisted probably in a per- 

 turbation of an equilibrium which tended toward a 

 stability unfavorable to vital activity. 258 



Now we have already seen how our hypothesis set 

 forth above is able to make at once conceivable in what 

 this equilibrium unfavorable to vital activity may consist. 

 According to this hypothesis, it would consist in the 

 equalization toward which the masses, and the corres- 

 ponding potentials, of the coupled accumulators of each 

 mnemonic element would tend, and which they would 

 eventually attain, and this equilibrium would be disturbed 

 by the substitution for one of these accumulators of an- 

 other specifically equal to it but differing in mass and 

 potential. And it is precisely in this function of fecunda- 

 tion, of replacing in each couple one of the specific 

 accumulators by another differing quantitatively as 

 widely as possible, that we find an explanation of the fact 

 that the rejuvenation of the germ and the consequent 

 vitality of the progeny to which fecundation tends, are 

 proportionally greater when fecundation occurs not be- 

 tween individuals too closely related but rather between 

 individuals which belong indeed to the same species but 

 are somewhat dissimilar. 



According to the same hypothesis, this equilibrium 

 could also be deranged by the extra-nuclear discharge of 

 one of the two coupled accumulators, and this is just what 



2G8 Spencer: Principles of Biology. I, P. 340 341, and II. P. 

 614616. 



