102 BIOLOGY OF PNEUMOCOCCUS 



enzymes, capable of attacking starch, inulin, and glycogen ; invert- 

 ases that convert complex saccharides into simpler sugars, and 

 other ferments that split these sugars into acids, while the acid so 

 formed arrests further proliferation of the bacterial cell. Intra- 

 cellular lipids are converted into fatty acids by pneumococcal 

 lipases and therefore the self-destruction of the cell may be com- 

 plete. Furthermore, the ingredients of the medium in which the or- 

 ganisms grow are largely replaced by a new order of constituents. 

 The action of all these enzymes may be reversible and by their ac- 

 tion or that of some similar agents Pneumococcus is able to build 

 protein, lipids, and somatic and capsular polysaccharides from 

 substances present in the substrate. 



In the operation of these vital processes, oxygen plays an im- 

 portant part. The element is essential to the hydrolysis and syn- 

 thesis of protein, lipid, and sugar but it may act in a variety of 

 ways. Some of the products of oxidation are inimical to the nor- 

 mal functioning of the bacterial cell and some affect changes in the 

 respiratory mechanism of the blood. Pneumococcus utilizes oxy- 

 gen to form peroxide that is toxic to the cell. Peroxide destroys the 

 labile constituents of the pneumococcal cell, which with the easily 

 oxidizable intracellular substance continue to form an oxidizing 

 substance responsible for the conversion of oxyhemoglobin into 

 methemoglobin. 



Pneumococcus, therefore, by the action of its intrinsic enzymes 

 may destroy itself and by the operation of its oxidation-reduction 

 system and its extracellular derivatives or products may, through 

 the dissolution of red cells, the conversion of oxyhemoglobin into 

 methemoglobin, and the lowering of oxygen capacity of the blood, 

 wreak serious damage to the tissues and pervert the normal physio- 

 logical functions of the body of the infected host. 



