30 CLINICAL BACTERIOLOGY. 



other bacteria, and especially the tetanus-toxin. They pre- 

 pared the toxic substances either by evaporation of filtered 

 bouillon-cultures in a vacuum at temperatures of from 20 

 C. (68 F.) to 35 C. (95 F.), and by precipitation of the 

 concentrated bouillon with absolute alcohol ; or they super- 

 saturated the bouillon-filtrate with ammonium sulphate or 

 sodium phosphate, and obtained from the precipitate the 

 poison, which proved to be not dialyzable. The poisons 

 thus obtained by alcoholic precipitation or separation by 

 means of salts yielded albuminoid reactions. They could 

 not be included among the globulins, as they were precipi- 

 table out of the bouillon-filtrate by the two salts named 

 only, and not by magnesium sulphate. Brieger and C. 

 Frankel named the toxic substances obtained, and which 

 appeared as amorphous powders, toxalbumins. These are 

 destroyed by temperatures of 60 C. (140 F.) ; according 

 to Buchner, the presence of neutral salts renders them 

 somewhat more resistant. These albuminoid powders cer- 

 tainly contain the specific bacterial poison ; with a minimal 

 amount of the powder obtained in this manner from tetanus- 

 bouillon, for instance, one can induce typical tetanus in 

 animals. Nevertheless, the bacterial poisons can not with 

 certainty be considered as albuminoid bodies. It is rather 

 more probable that the actual active bacterial poisons 

 are only carried down in the preparation of these albu- 

 minoid powders, and that they adhere to the albumin in a 

 purely mechanical manner, as it was possible to obtain with- 

 out difficulty specifically acting toxins by the growth of 

 pathogenic bacteria in nutritive media free from albumin. 

 (See Uschinsky's Nutritive Medium, p. 87.) 



In the course of further investigations of the tetanus- 

 toxin Brieger and Cohn also soon came to the conclusion 

 that this substance represents no true albuminoid body. A 

 notable advance in the knowledge of the nature of bacterial 

 toxins was made through the investigations of Brieger and 

 Boer. These investigators elicited the fact that the 

 poisons of diphtheria and of tetanus are precipitated from 

 their solutions, from filtered bouillon-cultures, by means of 

 heavy metals, in the form of more or less soluble double 

 combinations. A one per cent, solution of zinc chlorid 

 proved most available, being added in double the amount 

 of the toxin-solution. The double zinc-combinations thus 

 resulting no longer exhibit any of the well-known albu- 



