70 EFFECTS OF ADAPTATION sec. 



the properties, because they have the complete combination 

 of the whole. The higher animals, with more advanced 

 division of labour, cannot reproduce by division, because each 

 part does not contain the properties, the complete combination, 

 of the whole. In this sense the germ-cells alone are still in- 

 dividually complete elementary organisms, in relation to the 

 present question. 



Further, the Blastozoa,^ which reproduce only by germ- 

 cells, are only distinguished with respect to immortality from 

 the Protozoa, inasmuch as we are accustomed to regard their 

 soma as the essential part. But let us place ourselves at the 

 point of view indicated above, " that the soma is not really an 

 end in itself, but rather its principal function is to ensure the 

 maintenance of organic life by favouring reproduction," — let us 

 reflect a moment while we picture to ourselves the unbroken 

 chain of organic nature, its unity, and look upon the in- 

 dividual animals and plants as merely seed-vessels, — then the 

 Blastozoa appear as immortal as the Ablastozoa.- 



If we philosophise about nature at all, the naturalist who 

 desires to be thorough must not halt half-way. 



Thus the above way of regarding the matter is perfectly 

 justifiable — if the multicellular animals have really been 

 evolved little by little from the unicellular, it is a mere 

 self-evident consequence. 



Although, however, we may be willing to reason with as 

 much self-abnegation as is demanded by this conception, yet 

 by the above we are not compelled to go so far as to consider 

 death as useful, as an adaptation. 



Besides, Weismann himself speaks concerning the relation 

 between the germ-plasm of the multicellular organism on one 

 hand and of the unicellular on the other, and concerning the 

 significance of the body (soma) of the former, as follows : — 



^ Animals with germinal layers = Metazoa = multicellular animals. 

 - Animals without germinal layers = Protozoa = unicellular animals. 



