88 BIOLOGY OF PNEUMOCOCCUS 



mals recovered. The lesions reached maximal intensity within 

 twenty-four to forty-eight hours and disappeared in five to seven 

 days. Extracts prepared by the Avery-Neill method were more 

 potent than filtrates of pneumococcal cultures. Neither cultures 

 younger than eight to sixteen hours nor those that were very old 

 were active. Whole, unfiltered cultures rarely caused a reaction, 

 while bile-dissolved cultures produced no purpura, although bile 

 was shown not to inhibit this activity. The extracts induced pur- 

 pura in rabbits and guinea pigs as well as in white mice. Extracts 

 of Staphylococcus aureus, Streptococcus viridans and B. coli did 

 not exhibit this property. 



The purpura-producing principle withstands heating to 100° 

 for ten minutes; it resists oxidation; it is filter-passing; its activ- 

 ity is destroyed by digestion with trypsin ; and the substance can 

 be obtained from pneumococcal extracts by full saturation with 

 ammonium sulfate after the acetic acid-precipitable substances 

 have been removed. The principle is common to various pneumo- 

 cocci and apparently bears no relation to virulence, nor is it asso- 

 ciated with the hemotoxin of Pneumococcus, since the hemolytic 

 activity of an extract may be destroyed without affecting the pur- 

 purigenic property. 



Julianelle and Reimann concluded that the substance is a deg- 

 radation product of Pneumococcus. The authors had in previous 

 studies of experimental purpura found that excessive diminution 

 of blood platelets, due either to direct destruction of the cells or 

 damage to the seat of their origin, was a causative factor. In an- 

 other paper, Reimann and Julianelle 1130 reported variations in the 

 number of blood platelets in white mice injected with pneumococcal 

 extracts. The platelets were greatly diminished after injection, the 

 greatest decrease taking place after twenty-four hours. With a 

 count of less than 500,000 platelets per cubic millimeter of blood, 

 the mice usually developed purpura. A regeneration — an over- 

 regeneration — was accomplished by the fourth to the ninth day, 

 with a return to normal in about two weeks. The red cells were also 



