DEFENSIVE FERMENTS OF THE ANIMAL ORGANISM 35 



influence upon osmotic pressure, together with 

 others which are without this influence. In this 

 respect, too, the cell is always laid down on the most 

 delicate lines. Sometimes it decomposes colloidal 

 substances and transforms them into others, which 

 increase the osmotic pressure of the cell ; at other 

 times it synthesizes materials in solution into larger, 

 more complicated molecules, until a body appears 

 which is more and more extracted from the solution, 

 and by this means loses its influence upon the 

 osmotic pressure of the cell. This variety of function 

 is of great importance to the cell in quite a different 

 direction. We know that single ions exhibit very 

 specific activities. Here also the cell must be 

 equipped with arrangements to accelerate in one case 

 the action of a separate ion and to check those of 

 another, or else to entirely exclude them. The cell 

 is able to effect this in diverse ways. Sometimes an 

 ion is combined with a protein, for instance, or with 

 other substances, and so is robbed of its own 

 characteristics ; at other times an ion is set free 

 through decomposition or simple dissociation. Or else 

 the cell induces antagonistically acting ions to react 

 mutually on each other in finely graduated stages. 

 Numerous experiments have shown, as has already 

 been mentioned, that definite cells depend upon 

 definite secretions having their origin in other organs. 

 If we remove certain organs, for instance the thyroid 



