6 THE PHYSICAL BASIS OF LIFE 



held that it is by the transformation of these bodies that 

 many of the other formed bodies of the cell arise, includ- 

 ing the plastids, and various forms of granules and iibril- 

 lae; but the correctness of this view is still far short of 

 demonstration/ The Golgi-bodies are of still more doubt- 

 ful significance. They are known to play a definite part in 

 the formation of the sperm-cells, and evidence is begin- 

 ning to accumulate that they may be concerned in the 

 processes of secretion; but we niay feel sure that these 

 bodies are of far greater importance than this meager list 

 indicates, for they seem to be almost omnipresent in the 

 cells of animals and will probably be found as generally 

 in plant-cells. 



Some of these formed bodies seem to be permanent, 

 others to be transitory formations that come and go in the 

 kaleidoscopic operations of cell-life. Which of them are 

 alive i Which of them, if any, constitute the physical basis 

 of life ? What, in other words, is protoplasm '? 



These are embarrassing questions. One of the most 

 pleasing functions of the teacher of elementary biology 

 is to demonstrate to the laboratory student the substance 

 of a living cell, assuring him cheerfully that he is behold- 

 ing protoplasm ; and by good luck it rarely occurs to the 

 disciple to cross-examine his master on the subject. Were 

 it otherwise how many a bad quarter of an hour might we 

 have to endure ! For the truth is that the more critically 

 we study the question, the more evident does it become 

 that we can not single out any one particular component 

 of the cell as the living stuff, par excellence. Of this fact 

 most experienced cytologists, including such eminent 

 leaders as Flemming, Strasburger, Biitschli, Kolliker and 

 Heidenhain, long since became convinced. "No man," 

 said Flenuning, "can definitely say what protoplasm is. 

 ... In my view that which lives is the entire body of 



