3S DEFENSIVE FERMENTS OF THE ANIMAL ORGANISM 



so much division of labour is found, and to such 

 an extent, that a large number of cells are entirely 

 dependent upon the functions of others. Were such 

 cells to cease to work this would result, as has already 

 been mentioned, in the sickness and finally in the 

 death of many other cells. In this direction there 

 still lies an extensive field of research before us. The 

 " whys ' and the " wherefores ' in this case extend 

 indefinitely. 



The possibility of breeding single cells and 

 pieces of tissues in the blood plasma outside the 

 organism, and keep them alive for a certain time, 

 opens out a prospect of answering many problems 

 by experimental means. We shall see in due course 

 why some of the cells lose their normal functions 

 when the secretion of certain organs is lacking. The 

 number of possibilities is almost unlimited. For 

 example, some substances, such as grape sugar, can 

 only be dissociated by the cells into final products- 

 carbon dioxide and water after they have been pre- 

 pared in a certain manner. A gradual dissociation 

 takes place. The cell is equipped with appliances 

 for the alteration of a given substance, but they are 

 not at first in a condition suitable for use. A second 

 agent must first of all make them capable of their 

 respective functions just as a hammer without a 

 handle, or a screw without a screwdriver, are only 

 useful when the missing parts are at our disposal. 



