TOXINS OF THE TETANUS BACILLUS 425 



when a bouillon culture of the bacillus is filtered through 

 I>orcelain. To obtain it the fresh culture must be treated by 

 ammonium sulphate, as described in the method of obtaining 

 concentrated toxins (p. 195). This substance also has the 

 power of originating an antitoxin, so that certain antitetanic sera 

 can protect red blood corpuscles against its action. Madsen, 

 studying the interactions of this anti-tetanolysin with the 

 tetanolysin, has shown that phenomena can be demonstrated 

 similar to those noted by Ehrlich as occurring with diphtheria 

 toxin, and which the latter interpreted as indicating the presence 

 of degenerated toxins (toxoids) in the crude poison. With 

 tetanus as with diphtheria toxin the action of an acid is to 

 cause an apparent disappearance of toxicity, but if before a 

 certain time has elapsed the acid be neutralised by alkali, then a 

 degree of the toxicity returns. 



As with other members of the group, nothing is known of the 

 nature of tetanus toxin. Uschinsky has found that the tetanus 

 bacillus can produce its toxin when growing in a fluid containing 

 no proteid matter. The toxin may thus be formed independently 

 of the breaking up of the proteins on which the bacillus may be 

 living, though the latter no doubt has a digestive action on such 

 a protein as gelatin. There is, however, evidence that peptic 

 digestion and toxin formation are due to different vital processes 

 on the part of the tetanus bacillus. 



Whatever the nature of the toxin is, it is undoubtedly one 

 of the most powerful poisons known. Even with a probably 

 impure toxalbumin Brieger found that the fatal dose for a 

 mouse was '0005 of a milligramme. If the susceptibility of 

 man be the same as that of a mouse, the fatal .dose for an average 

 adult would have been '23 of a milligramme, or about -^V^ths 

 of a grain. Animals differ very much in their susceptibilities 

 to the action of tetanus toxin. According to v. Lingelsheim, if 

 the minimal lethal dose per gramme weight for a horse be taken 

 as unity, that for the guinea-pig would be 6 times the amount, 

 the mouse 12, the goat 24, the dog about 500, the rabbit 1800, 

 the cat 6000, the goose 12,000, the pigeon 48,000, and the 

 hen 360,000. 



A striking feature of the action of tetanus toxin is the 

 occurrence of a definite incubation period between the introduc- 

 tion of the toxin into an animal's body and the appearance of 

 symptoms. The incubation period varies according to the species 

 of animal employed, and the path of infection. In the guinea- 

 pi i: it is from thirteen to eighteen hours, in the horse five days, 

 and the incubation is shorter when the poison is introduced into 



