422 LAWS 01 MULTIPLICATION. 



these highest groups, to which the largest members of the 

 vegetal kingdom belong, is that agamogenesis has so far 

 ceased that it does not originate independent plants. Though 

 the axes which, budding one out of another, compose a tree, 

 are the equivalents of asexuallj'-produced individuals ; yet 

 the asexual production of them stops short of separation. 

 These vast integrations arise where spontaneous disintegra- 

 tion, and the multiplication effected by it, have come to an 

 end. 



Thus, not forgetting that certain Phsenogams, as Begonia 

 phyllomaniaca, revert to quite primitive modes of increase, we 

 may hold it as beyond question that while among' the most 

 minute plants asexual multiplication is universal, and pro- 

 duces enormous numbers in short periods, it becomes step by 

 step more restricted in I'ange and frequency as we advance to 

 large and compound plants ; and disappears so generally 

 from the largest, that its occurrence is regarded as anomalous. 



§ 336. Parallel examples showing the inverse variation of 

 growth and asexual genesis among animals, make clear the 

 purely quantitative nature of this relation under its original 

 form. Of the Amoeba it is said that " when a large variable 

 process has been shot out far from the chief mass and become 

 enlarged at the extremity, the expanded end retains its posi- 

 tion, whilst the portion connecting it with the body becomes 

 finer and finer by being withdrawn into the parent mass, 

 until it at last breaks across, leaving a detached piece, which 

 immediately on its own account shoots out processes, and 

 manifests an independent existence. This phenomenon is 

 therefore one of simple detachment, and cannot rightly be 

 called a process of fission." But it shows us, nevertheless, 

 how the primordial form of multiplication is nothing more 

 than a separation, instead of a continued union, of the grow- 

 ing mass. Among the Protozoa, as among the 

 Frotophyta, there occurs that process by which the in- 

 dividuality of the parent is wholly lost in producing offspring 



