VALUE OF TETANUS ANTITOXIN 55 



10 c.c. of the Pasteur Institute serum is equal to 

 about 600 U.S.A. units. By remembering the above 

 figures and noting the make of the serum, we can 

 estimate the number of units contained in a dose of 

 each individual serum. 



Experimental Value of Antitoxin. — From labora- 

 tory experiments, there can be no doubt that tetanus 

 antitoxin, if given along with or shortly after a dose 

 of toxin, has the power of preventing the characteristic 

 symptoms and of death. Accordingly, as the time 

 between the injection of toxin and antitoxin increases, 

 so must the quantity of antitoxin increase if its 

 beneficial effects are to occur. Kraus and Amiradziti 

 further showed that the antitoxin does not penetrate 

 the toxin-loaded cells, but that the toxin must diffuse 

 out before it can be neutralised, the rate of diffusion 

 being accelerated by the presence of a high concentra- 

 tion of antitoxin in the surrounding fluid. But there 

 comes a time when the toxin has entered so closely 

 into combination with the cells that no amount of 

 antitoxin is capable of withdrawing it. After this 

 time even the minimal lethal dose is of necessity 

 fatal. 



Further, even if the blood of an animal is rendered 

 antitoxic to tetanin, injection of this poison into 

 the substance of its brain will still produce the fatal 

 effects. 



Prevalence of Tetanus. — Tetanus is a common 

 disease of the domesticated animals, especially among 

 equines, and in most cases is fatal. Before any 



