46 THE NATURE AND ORIGIN OF LIFE 



Cell-membrane 



- Cytoplasm 



Nucleus 



means of investigation with regard to chemical structure 

 and the colloid state. If we kill a cell by means of osmic 

 acid or mercury bichloride, the existence of the two distinct 

 colloids the cytoplasm and the nucleus becomes still 

 plainer. In other words, we find the same structural char- 

 acter in the dead cell as in the living cell. From this we must 

 not conclude that this structural character is not character- 

 istic of life, but rather that, with our imperfect means of 

 research, we cannot distinguish the living whole " cyto- 



plasm-nucleus " from the 



f 



dead aggregate corpse or 



the cytoplagm and corpse 



of the nucleus." 



Let us seek elsewhere. 

 It was long believed that 

 spontaneous movement was 

 characteristic of life. It 

 has been found necessary to give up this opinion, first, 

 because the pretended spontaneousness has been shown to 

 be a result of chemical reactions and osmotic changes, and, 

 then, because in dead substances such spontaneous move- 

 ments have been discovered (Brownian Movement). 



This question of the movement of living bodies has to 

 be studied later ; it is enough for the present to know that 

 from its study we can derive the elements of the definition 

 of life. 



The living being grows, develops, dies, say the most an- 

 cient definitions. In this first character growth we find 

 that which discriminates life ; and this is all the more sin- 

 gular that the character is not observable in those beings 

 which for us are, as it were, the very type of life, namely, 

 adult men and animals. 



In return, this character of growth is evident in familiar 



