THE WONDERS OF LIFE 



quantity in the plasm. On this depends the capacity for 

 absorption or imbibition in the plasm, and the mobility 

 of its molecules, which is very important for the per- 

 formance of the vital actions. However, this capacity 

 of absorption has definite limits in each variety of 

 plasm; living plasm is not soluble in water, but abso- 

 lutely resists the penetration of any water beyond this 

 limit. 



The chemistry of living matter is the most important 

 1 and interesting, but at the same time the most difHcult 

 and obscure, part of the whole of biological chemistry. 

 In spite of the innumerable and careful investigations 

 which have been made of it by the ablest physiologists 

 and chemists in the second half of the nineteenth 

 century, we are still far from a satisfactory solution of 

 this fundamental problem of biology. This is due partly 

 to the extraordinary difficulty of isolating pure living 

 plasm and subjecting it to chemical analysis, and partly 

 to the many errors and misunderstandings that have 

 arisen through one-sided treatment of the subject, and 

 especially through confusion of the chemical and 

 morphological features of plasm. We can thus under- 

 stand the contradictory views that are still put forward 

 by distinguished chemists and physiologists, zoologists 

 and botanists. As I cannot deal here with the very 

 extensive, elaborate, aifd contradictory literature of the 

 subject, I must be content to give a brief summary of 

 the conclusions I have reached by my reading and my 

 own studies of plasm (begun in 1859). 



To begin with, we must clearly understand that proto- 

 ^plasm — in the most general sense in which we here take 

 it — is a chemical substance, not a "mixture of different 

 substances," or a "mixture of a small quantity of solid 

 matter with a good deal of fluid. ' ' As Richard Neumeister 

 very well observes: "We seek the nature of protoplasm 

 in the peculiar processes which take place in its con- 



124 



