BIOCHEMICAL FEATURES 101 



molecular size, even to whole unsplit proteins, remaining in diges- 

 tion mixtures. Traces of intact proteins acting as antigens may be 

 responsible for the weak neutralizing power of the serum of ani- 

 mals treated with extracts, filtrates, and autolysates of Pneumo- 

 coccus or, what is more probable, such feeble and transient resist- 

 ance as these antigens induce is merely the tolerance established by 

 degraded proteins and not immunity. 



While it is possible that a true toxin may be a constituent of the 

 pneumococcal cell or a product of its metabolic processes, until 

 more convincing evidence is presented, it would seem reasonable to 

 look upon these so-called "toxic" effects as being referable to the 

 action of bacterial protein poisons. 



Summary 



It may assist the reader to gain a clearer conception of the rela- 

 tion of the biochemical phenomena manifested by this bacterial 

 cell to the morbid processes induced by the living organism to se- 

 lect from the mass of data the more significant discoveries and to 

 weave them together into a summary. Pneumococcus is a fragile 

 body and contains within itself enzymatic forces that lead to its 

 disruption and disintegration, rob the substrate in which it lives of 

 nutrient substances, and from these substances evolve chemical 

 agents that arrest further growth, cause the death of the organ- 

 ism, and affect the cells of the animal body into which the microbe 

 may find its way. 



Intracellular proteases break down the proteins of the cell and 

 of the substrate upon which the cell feeds into smaller fragments, 

 which in turn are still further reduced in size by the same ferment 

 or possibly by a peptidase. This proteolysis reduces the food sup- 

 ply in the medium, and the products of the digestive action may in- 

 duce purpura and cause other more or less violent toxic effects in 

 the animal host. The poisonous principles, as far as can be learned, 

 are not true toxins, but resemble degraded proteins in their physio- 

 logical action. Pneumococcus is also endowed with saccharolytic 



