122 THEORETICAL BIOLOGY 



machines do not possess. Every living thing proceeds from 

 protoplasm ; traces of it remain in every cell, where it 

 forms that part of the cell which does not pass over into the 

 mechanical framework of the whole. And the protoplasm as 

 a whole is kept in continuity throughout the body by means 

 of fine connecting strands. 



The anatomically demonstrable existence of protoplasm 

 permits us to assume a fundamental division between the 

 mechanical framework and the protoplasmic net that traverses 

 the entire body, and to ascribe to the latter all the super- 

 mechanical powers. 



When this separation is made, we realise that an organism 

 without its protoplasm represents an ideal machine. This 

 skilfully interwoven bundle of reflex-arcs, with its perfectly 

 constructed receptors and effectors, has become an inde- 

 pendent machine, responding to the influences of the outer 

 world by means of its own actions. But these actions are 

 quite unalterable and automatic, and it is here that we see 

 demonstrated the most essential contrast between what is 

 living and what is dead. If, in virtue of its framework, a 

 creature behaved physiologically like a living organism, but 

 nevertheless was without protoplasm, we should be obliged to 

 describe it as dead. 



PROTOPLASM 



Protoplasm, as it is found in all living cells from the germ- 

 cell onwards, also possesses a mechanical framework, for it 

 exhibits the fundamental mechanical actions of the living 

 organism ; it is capable of movement, metabolism, ingestion 

 of food and so on. One of the chief things it does, i.e. cell- 

 division, requires, indeed, a very complicated mechanism. 



If this were all that we might expect of protoplasm, then 

 we should have in it nothing more than another machine incor- 

 porated in the large one. 



