BIOCHEMICAL FEATURES 97 



pneumococcus infections." In the light of later events this claim 

 and hope would seem to be premature. Larson, 787 with pneumococ- 

 cal filtrates supplied by Olson, found the same congestion of the 

 lungs in white mice injected intraperitoneally. Of skin tests per- 

 formed with the filtrates, those on pneumonia convalescents were of 

 possible significance in being uniformly negative. Larson voiced the 

 same conviction that the filtrates contained a soluble toxin. 



In a second paper, Olson, 1030 after describing the lesions pro- 

 duced by pneumococcal filtrates in mice, went so far as to say that 

 the toxin was an exotoxin and not an autolytic product or endo- 

 toxin, and gave as his reason that eight-hour culture filtrates pos- 

 sessed marked toxicity but contained little hemotoxin. The toxic 

 principle was relatively thermostable, but was completely destroyed 

 by boiling for one hour. While unpreserved lots lost activity, 0.3 

 per cent cresol served to maintain the toxicity for several months 

 regardless of the temperature. Active immunization of mice by se- 

 rial injections of the toxin resulted in protection against 1,000 to 

 10,000 fatal doses of pneumococci, while the specificity of the im- 

 munity induced bore no relation to the serological type of the or- 

 ganism from which the so-called toxin was obtained. The stability 

 of the toxic principle in the presence of heat, the stabilizing action 

 of cresol, and the lack of specificity are, as we know, characters 

 not shared by true exotoxins. 



The report of Parker and Pappenheimer 1063 takes us back to the 

 toxic action of autolysates. Solutions were prepared by allowing 

 a suspension of pneumococci, sealed in tubes under vaseline, to 

 stand in the dark at 22° to 24° for two to five days and then in the 

 ice-box. The autolysates were centrifuged in the cold, the seals 

 opened, and the clear supernatant fluid passed through a well-iced 

 Berkefeld filter. The filtrate injected intratracheally in a dose of 

 0.2 cubic centimeters was highly toxic for guinea pigs, death tak- 

 ing place either within a few hours or within three days. In animals 

 succumbing early, there was intense hemorrhagic edema of the 

 lungs with beginning inflammatory reaction ; in animals surviving 



