204 THE STORY OF LIFE'S MECHANISM. 



really exist in living protoplasm, while the mar- 

 vellous activities described are found only in the 

 highly organized cell, but do not belong to simple 

 protoplasm. It is claimed that simple protoplasm 

 consists of a physical mixture of two different 

 compounds, which form a foam when thus mixed, 

 and that much of the described structure of proto- 

 plasm is only the appearance of this foam. This 

 conception is certainly not the prevalent one 

 to-day ; and even if it should be the proper one, 

 it would still leave the cell as an extremely com- 

 plicated machine. Under any view the cell is a 

 mechanism, and must be resolved into subordi- 

 nate parts. It may be uncertain whether these 

 subordinate parts are to be regarded simply as 

 chemical compounds physically mixed, or as 

 smaller units, each of which is a smaller mechan- 

 ism. At all events, at the present time we know 

 of no such simple protoplasm capable of living 

 activities apart from machinery, and the problem 

 of explaining life, even in the simplest form 

 known, remains the problem of explaining a 

 mechanism. 



THE ORIGIN OF THE CELL MACHINE. 



We have thus set before us another problem, 

 which is after all the fundamental one, namely, 

 to ask whether we can tell anything of nature's 

 method of building the protoplasmic machine. 

 The building of the higher animal and plant, as 

 we have seen, is the result of the powers of 

 protoplasm; but protoplasm itself is a machine. 

 What has been its history 1 



