THE ANAEROBIC BACILLI 733 



the most susceptible species in proportion to their body weight. The 

 common domestic fowls are extremely resistant. Calculated for 

 grams of body weight, the horse is twelve times as susceptible as 

 the mouse, the guinea-pig six times as susceptible as the mouse. 

 The hen, on the other hand, is 200,000 times more resistant than the 

 mouse. 



After the inoculation of an animal with tetanus toxin there is 

 always a definite period of incubation before the toxic spasms set 

 in. This period may be shortened by increase of the dose, but never 

 entirely eliminated. 24 When the toxin is injected subcutaneously, 

 spasms begin first in the muscles nearest the point of inoculation. 

 Intravenous inoculation, 25 on the other hand, usually results in 

 general tetanus of all the muscles. . The feeding of toxin does not 

 produce disease, the poison being passed through the bowel un- 

 altered. 



The harmful action of tetanus toxin is generally attributed to 

 its affinity for the central nervous system. Wassermann and Takaki 26 

 show that tetanus toxin was fully neutralized when mixed with 

 brain substance. Other organs liver and spleen, for instance 

 showed no such neutralizing power. The central origin of the tetanic 

 contractions was made very evident by the work of Gumprecht, 27 

 who succeeded in stopping the spasms in a given region by division 

 of the supplying motor nerves. 



The manner in which the toxin reaches the central nervous system 

 has been extensively investigated, chiefly by Meyer and Ransom, 

 and Marie and Morax. Meyer and Ransom 28 from a series of careful 

 experiments reached the conclusion that the toxin is conducted to 

 the nerve centers along the paths of the motor nerves. Injected 

 into the circulation, 29 the toxin reaches simultaneously all the motor 

 nerve endings, producing general tetanus. In this case too, there- 

 fore, the poison from the blood can not pass directly into the central 

 nervous system, but must follow the route of nerve tracts. 



These observations have been of great practical value in that they 

 pointed to the desirability of the injection of tetanus antitoxin 



24 Courmont et Doyen, Arch, de phys., 1893. 



25 Ransom, Deut. med. Woch., 1893. 



26 Wassermann und Takaki, Berl. kiln. Woch., 1898. 



27 Gumprecht, Pfluger's Arch., 1895. 



28 Meyer und Ransom, Arch., f . exp. Pharm. u. Path., xlix. 



29 Marie et Morax, Ann. de 1'inst. Pasteur, 1902. 



