PROTECTIVE INOCULATIONS. 



to rabbits, and a few drops injected subcutaneously sufficed to kill a 

 small bird within a few hours. In their second paper (1889) the 

 authors mentioned state that so long as the reaction of a culture in 

 bouillon is acid its toxic power is comparatively slight, but that in 

 old cultures the reaction is alkaline, and in these the toxic potency is 

 greatly augmented. With such a culture, filtered after having been 

 kept for thirty days, a dose of one-eighth of a cubic centimetre in- 

 jected subcutaneously, sufficed to kill a guinea-pig; and in larger 

 amounts it proved to be fatal to dogs when injected directly into the 

 circulation through a vein. 



The same authors, in discussing the nature of the poison in their 

 filtered cultures, infer that it is related to the diastases, and state that 

 its toxic potency is very much reduced by exposure to a comparatively 

 low temperature 58 C., for two hours and completely destroyed by 

 the boiling temperature 100 C C., for twenty minutes. It was found 

 to be insoluble in alcohol, and the precipitate obtained by adding al- 

 cohol to an old culture proved to contain the toxic substance. Loffler 

 also has obtained, by adding five volumes of alcohol to one of a pure 

 culture, a white precipitate, soluble in water, which killed rabbits in 

 the dose of 0.1 to 0.2 gramme when injected beneath the skin of these 

 animals. It gave rise to a local oedema and necrosis of the skin in 

 the vicinity of the point of inoculation, and to hyperaemia of the in- 

 ternal organs. This deadly toxin appears to be an albuminoid sub- 

 stance, but its exact chemical composition has not yet been deter- 

 mined. 



Brieger and Frankel (1891) obtained results corresponding with 

 those previously reported by Roux and Yersin. Their researches 

 showed that the toxic substance contained in diphtheria cultures is 

 destroyed by a temperature of 60 C. ; that it is soluble in water, and 

 insoluble in alcohol; that it does not pass through a dialyzing mem- 

 brane, and has not the chemical characters of the ptomaines or toxins, 

 but is an albuminous body a toxalbumin. It w r as obtained by the 

 authors named by precipitation with slightly acidified (acetic acid) 

 alcohol; the precipitate, after being washed in a dialyzer and dried 

 in a vacuum at a temperature of 40 C., was a snow-white, amorphous, 

 crumbling mass. 



Wassermann and Proskauer (1892) found that the alcoholic pre- 

 cipitate from diphtheria cultures contains two different substances, 

 which are distinguished by their different degrees of solubility in 

 dilute and absolute alcohol ; both, however, give the usual reactions 

 of albuminous bodies, and pass very slowly through a dialyzing mem- 

 brane. Only one of these substances possesses toxic properties. 



