82 BACTERIOLOGY. 



On the other hand, the waste-products are formed in the 

 cell and are excreted. They result from a tearing--down, or 

 cleavage of more complex bodies and, therefore, are to be 

 considered as analytic products. 



Inasmuch as the compounds mentioned are formed 

 within the cell they may be designated d^s primary products. 

 These should be distinguished, as far as possible, from the 

 secondary products which are formed wholly on the outside 

 of the cell. Thus, the ferment produced within the cell may 

 be eliminated and may then .act upon suitable material on 

 the outside. The pepsin of the gastric juice is secreted by 

 certain cells of the stomach and, whether in the stomach or 

 in a test-tube, it will digest or split up albumin into simpler 

 bodies such as albumose, or pepton. In like manner, the fer- 

 ment produced by bacteria may act upon various substances 

 and give rise to cleavage products. Again, certain bacteria 

 produce compounds which unite with the oxygen of the air 

 to form bright-colored pigments. In either case, the pro- 

 ducts are not made directly by the cell and for this reason 

 they may be spoken of as secondary. 



Bacterial proteins. — The albuminous substances which 

 are formed within the cell, and which constitute an integral 

 part of the cell protoplasm, are known as the bacterial 

 cellular proteins. Very little is known in regard to their 

 exact chemical composition. The cellular proteins of some 

 bacteria possess a marked action upon the animal body. 

 They may cause suppuration, or may possess a decided 

 poisonous action. 



Secondary bacterial proteins are formed outside of the 

 cell, in the culture medium, by the action of the soluble 

 ferments secreted by the organisms. Various albuminous 

 substances may consequently be found in the liquid in 

 which bacteria are growing. Thus, the coagulated white 

 of an e.gg, or ordinary blood-fibrin, may be dissolved and 

 changed to an albumose. If the ferment is very active the 



