84 BIOLOGY: GENERAL AND MEDICAL 



Protoplasm stands at the head of a list of compounds 

 known as proteins, some of which are well-known, yet 

 not one of which is correctly known as regards its true 

 chemical composition. The reason becomes obvious 

 when a few of the formulae suggested are examined. 

 Thus one chemist who studied the hemoglobin from 

 the dogs' blood finds it represented by the formula 

 C 726 H 1171 N 194 O 214 S 3 . One of the various formulae sug- 

 gested for egg-albumen is C 204 H 322 N 52 O 66 S 2 . The com- 

 plexity is so great that no two chemists arrive at the 

 same result. If such is the complexity of fixed and 

 relatively stable egg-albumen, how much more elaborate 

 the structure of the subtle and evanescent living proto- 

 plasm must be we can scarcely conjecture. 



Gustav Mann, however, very properly points out 

 that we may fall into error in this particular. He says : 

 "To many people a living cell consists of 'protoplasm/ 

 a substance they imagine to be one exceedingly complex 

 body. They do not realize that in a cell we have a not 

 very large number of comparatively simple compounds 

 which only collectively form the protoplasm. What 

 constitutes life is the presence of a number of such 

 'organic' compounds capable of mutually reacting upon 

 one another, and thereby giving rise to new compounds, 

 which cannot react chemically with the mother sub- 

 stance from which they are derived, but which by 

 interacting with new radicals give rise to a cycle of 

 events." 



To learn the process by which protoplasm is built up, 

 one might imagine that the simplest method would be to 

 follow the successive steps in its disintegration, learn the 

 products of its analysis, and then, by retracing the steps 

 from the simple to the complex, arrive at an approxi- 

 mately accurate result. 



It is true that when protoplasm dies it undergoes a 

 speedy dissolution, terminating in a number of well- 

 known simple compounds, but though the stages in the 

 disintegration process seem to be so brief, the successive 



