THE ACTIVE FORCES OF LIVING ORGANISMS 17 



during or previous to the act of observation. This 

 reasoning might possibly apply to some cells, but it 

 could not be advanced to explain the lack of a nucleus 

 in the red corpuscles of the blood of mammals. The 

 only way out of the difficulty would seem to lie in the 

 contention that the red corpuscles are not cells in the 

 proper sense of the term. But though this may be 

 true, what are we to say of the red corpuscles of the 

 lower animals, which are distinctly nucleated ? How 

 can we explain this peculiarity, bearing in mind that 

 a nucleus is recognised by all observers to be the most 

 essential part of a cell ? Are we to classify the one 

 set of corpuscles as cells and not the other ? * 

 One might at first sight be inclined to connect the ^,^^ "^^^^ 



° "^ of the 



presence or absence of a nucleus with the rate of nucleus in 



the blood 



tissue-change, smce very many of the creatures pos- corpuscles 

 sessing nucleated corpuscles belong to the cold-blooded and rep- 

 class, whose vital functions are strikingly slow. Thus, 

 a salamander can live without food for six months ; a 

 toad for two, and fresh-water polypi for five or ten 

 years ; whilst a snail, after six weeks of abstinence, 



* Quain's ' Anatomy,' p. 29 : ' The aflftrmation of Bottscher 

 that a nucleus is present in the mammalian red blood corpuscle 

 rests entirely upon erroneous methods of preparation. That of 

 Strieker (which is a revival of the older opinions of Wharton 

 Jones, and of Busk and Huxley), that the mammalian red cor- 

 puscle is, morphologically, a nucleus with an imperceptible 

 amount of enveloping cell-substance, is quite distinct from 

 Bottsoher's view, and has certain considerations to recommend 

 it, but is supported at present upon an insufficient basis of fact, 

 and is opposed, moreover, to recent observations upon the de- 

 velopment of the red disc' 



2 



