PHYSICO-CHEMICAL PROPERTIES 85 



(e) AV'heii the "N" and "P"' tractions were completely re- 

 moved by repetition of procedures (b) , (c) , and (d) , including 

 several alcoholic precipitations from alkaline as well as acid solu- 

 tions, the final alcoholic precipitate was designated as the "C" 

 fraction. 



This author treated a nimiber of various bacterial preparations 

 by means of the above methods and tested the fractions obtained 

 for skin-preparatory potency. A series of injections into the skin 

 of the shaved back ^vas made. Each material ^vas injected in foin^ 

 to H\e different dilutions. "Agar ^vashings" filtrates of kno^vn 

 potency were injected intravenously tw^enty-four hours later. Most 

 of his work ^^•as done with fractions of "agar ^vashings" filtrates. 

 Only weak reactions were oljtained with the lowest dilutions of 

 the N-fractions and were interpreted as contaminations by other 

 fractions. The freshly prepared C-fraction regularly sho^ved a high 

 degree of activity ^vhich often approximated the action of the 

 corresponding amoimt of whole filtrate. The Molisch tests ^vith 

 the C-fraction ^vere ahvays strongly positi\e ^vhilst in several in- 

 stances the material was found biuret-negative. This fraction 

 showed a higii degree of lability and lost its activity if stored in 

 the ice box in Avatery solution for forty-eiglit horns. In a few 

 cases the C-fractions remained stable long enough to permit an 

 attempt at further purification. The solutions were satiuated with 

 annnonium sulphate and a fine precipitate formed ^\hich Avas 

 separated by centrifugalization and dialysis against running ^vater. 

 The dialysis proved deleterious to the active substance. The 

 P-fraction obtained from "agar washings" of B. typJwsus varied 

 considerably in amount. The largest P-fractions were found ^vhen 

 the bacterial cells imderwent autolysis. The P-fraction was active 

 in all cases and more stable than the C-fraction. It usually gave 

 positi\e biuret reaction and a strong Molisch test. The potency 

 of the P-fraction was conditioned by the amount obtained and 

 this in turn by the occurrence of autolytic processes. 



Binnet (1931) and other investigators obtained a high degree 

 of activity in whole bacteria and their extracts when prepared 

 according to Besredka's method. I foinid by comparative titra- 

 tions a superiority of "agar washings" filtrates to bacterial ex- 

 tracts. It is possible, as Apitz points out, that the residts may vary 

 with the ability of the strains to form active principles of ex- 

 ogenous or endogenous origin. 



Apitz also obtained active C- and P-fractions from ground li\e 



