28 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



on the other hand, all attempts to conceive the organism as 

 a mere aggregate of cells have proved to be wrong. It is 

 the whole that uses the cells, as we shall see later on, or 

 that may not use them : thus there is nothing like a " cell- 

 theory," even in a deeper meaning of the word. 



The cell may have the most different forms : take a cell 

 of the skin, of a muscle, of a gland, of the wood in plants 

 as typical examples. But in every case two parts may be 

 distinguished in a cell : an outside part, the protoplasm, and 

 an inside part, the nucleus, to leave out of special account 

 several others, which, by the way, may only be protoplasmatic 

 modifications. 



Protoplasm is a mere name for what is not the nucleus ; 

 in any case it is not a homogeneous chemical compound ; 

 it consists of many such compounds and has a sort of 

 architecture ; all organic functions are based upon its 

 metabolism. The nucleus has a very typical structure, 

 which stands in a close relation to its behaviour during the 

 most characteristic morphological period of the cell : during 

 its division. Let us devote a few words to a consideration 

 of this division and the part the nucleus plays in it ; it 

 will directly bear on future theoretical considerations about 

 development. 



There is a certain substance in every nucleus of a cell 

 which stains most markedly, whenever cells are treated with 

 pigments : the name of " chromatin " has been given to it. 

 The chromatin always gives the reaction of an acid, while 

 protoplasm is basic ; besides that it seems to be a centre of 

 oxidation. Now, when a division of a cell is to occur, the 

 chromatin, which had been diffusely distributed before, in 

 the form of small grains, arranges itself into a long and 



