CHAPTER VI. 



ANTAGONISM BETWEEN GROWTH AXD SEXUAL GENESIS. 



338. IN so far as it is a process of separation,, sexual 

 genesis is like asexual genesis ; and is therefore, equally with 

 asexual genesis, opposed to that aggregation which results in 

 growth. Whether deduction is made from one parent or 

 from two, whether it is made from any part of the body 

 indifferently or from a specialized part, or whether it is made 

 directly or indirectly, it remains in any case a deduction; 

 and in proportion as it is great, or frequent, or both, it must 

 restrain the increase of the individual. 



Here we have to group together the leading illustrations 

 of this truth. We will take them in the same order as 

 before. 



339. The lowest vegetal forms, or rather, we may say, 

 those forms which we cannot class as either distinctly vegetal 

 or distinctly animal, show us a process of sexual multiplica 

 tion that differs much less from the asexual process than in 

 the higher forms. The common character which distinguishes 

 sexual from asexual genesis, is that the mass of protoplasm 

 whence a new generation is to arise, has been produced by the 

 union of two portions of matter which were before more wide 

 ly separated. I use this general expression because, among 

 the simplest Algcc, this is not invariably matter supplied 

 by different individuals : certain Diatomaccce exhibit within 

 a single cell, the formation of a sporangium by a drawing 

 448 



