No. 593] 



THE EVOLUTION OF THE CELL 



27! 



used in a sense quite different from its ordinary sig- 

 nificance. 32 



In addition to the highly developed structural differen- 

 tiation of the body the Infusoria exhibit the extreme of 

 specialization of the nuclear apparatus in that they pos- 

 sess, as a rule, two distinct kinds of nuclei, micronuclei 

 and maeronuclei, composed respectively of generative 

 and trophic chromatin, as already pointed out. This fea- 

 ture is, however, but the culminating point in a process 

 of functional specialization of the chromatin which can be 

 observed in many Protozoa of other classes, and which, 

 moreover, is not found invariably in its complete form in 

 all Ciliata. 



In this address I have set forth my conceptions of the 

 nature of the simplest forms of life and of the course taken 

 by the earliest stages of evolution, striving all through to 

 treat the problem from a strictly objective standpoint, and 

 avoiding as far as possible the purely speculative and 

 metaphysical questions which beset like pitfalls the path 

 of those who attack the problem of life and vitalism. I 

 have, therefore, refrained as far as possible from discuss- 

 ing such indefinable abstractions as " living substance" or 

 "life," phrases to which no clear meaning can be attached. 



How far my personal ideas may correspond to objective 

 truth I could not, of course, pretend to judge. It may be 

 that the mental pictures which I have attempted to draw 

 are to be assigned, on the most charitable interpretation, 

 to the realm of poetry, as defined by the greatest of poets, 

 rather than of science. 



The lunatic, the lover and the poet 



»rth 



If I might be permitted to attempt an impartial criti- 

 cism of my own scheme, I think it might be claimed that 



» 2 See Appendix A. 



