BIOCHEMICAL FEATURES 91 



the preparations of cellular carbohydrate. This substance, what- 

 ever might have been its nature, in addition to being heat-stable, 

 was neutralized by Type I antipneumococcic serum even when the 

 latter had been adsorbed with either the homologous soluble spe- 

 cific substance or the cellular carbohydrate. Sickles and Shaw re- 

 ported that this purpura-producing activity of the polysaccharide 

 was destroyed when the carbohydrate was subjected to the action 

 of its appropriate carbohydrate-decomposing enzyme, but there is 

 no evidence to be found in the communication that the presence of 

 proteolytic ferments in the enzymatic extract had been excluded. 

 The weight of evidence favors the view that the substance re- 

 sponsible for the purpuric manifestations is a cleavage product of 

 pneumococcal protein, arising in the lysis of the bacterial cell and 

 that purpura production is not a property of any of the compo- 

 nents of Pneumococcus as they exist in the normal bacterial cell. 



Virulin, Leucocidin, and Analogous Substances 

 Poisoning and dissolution of red blood corpuscles and the elabo- 

 ration of purpurigenic substances are not the only ways in which 

 Pneumococcus attacks body tissues. Saline extracts of the coccus, 

 prepared by Rosenow's method, were reported by Pittman and 

 Falk 1092 to decrease phagocytosis of avirulent organisms, to reduce 

 the opsonic content of serum, and only slightly to increase the 

 virulence of a borderline culture after it had been transferred sev- 

 eral times in the presence of the extract. The extracts failed to in- 

 fluence the virulence of an avirulent Pneumococcus. The principle 

 contained in the extract, prepared by incubating dense suspen- 

 sions of pneumococci in small volumes of isotonic sodium chloride 

 solution with subsequent heating and centrifuging, the authors 

 named "Virulin." Considering the feeble action of the substance in 

 raising the virulence of pneumococci, the name would seem to be 

 too specific a designation for an unidentified substance. 



Another toxic principle of Pneumococcus is the "Leucocidin" 

 described by Oram, 1032 who reported that in actively growing cul- 



