TETANUS TOXIN 87 



only the gray matter and not the white substance of the brain possesses this absorption 

 power. If the brain emulsion is boiled, it loses this affinity for the toxin. 



Concerning the way by which the toxin reaches the central nervous 

 system, opinions vary. Most writers, especially Meyer and Ransom, 

 consider that the journey is made along the nerve paths. Zupnik on 

 the other hand believes that it is distributed through the blood stream and 

 is taken up not only by the nervous system, but also to a great extent by 

 the muscles. 



That tetanus toxin is very labile is well known. According to Kitasato, 

 five minutes at 65 C. or twenty minutes at 60 C. is sufficient to weaken 

 the toxicity to a great extent, in fact almost to destroy it. Light has a 

 similar effect upon it. Careful as its preservation may be, the soluble 

 tetanus toxin soon becomes attenuated. Hence the best way of keeping 

 it in stock is in a dry form. For estimating the strength of the toxin 

 white mice are employed and are injected subcutaneously with fresh sol- 

 uble toxin, the lethal dose being the amount which kills the animals in four 

 to five days. Animals more susceptible than mice are horses, they being 

 twelve times as sensitive and guinea-pigs six times as much. Hens 

 possess greater power of resistance, being 30,000 times less susceptible to 

 the toxin than mice. 



Tetanolysin acts upon the red blood cells and disintegrates them. The 

 erythrocytes of goats, sheep and horses, are best suited for experiments to 

 demonstrate this action. Ehrlich showed that the tetanolysin and the 

 tetanospasmin are really two distinctly different toxins and not one toxin 

 with a twofold function. When tetanus poison is mixed with red blood 

 cells the tetanolysin is absorbed and the tetanospasmin remains free. 

 Even the antitoxins of these two are different. 



As far as the standardization of the tetanus serum is concerned, it 

 follows along the same lines as the diphtheria serum, i.e., the L + dose 

 of toxin being the one employed. 



"In America the method of standardization was regulated by a law 

 passed in July, 1908, based upon the work of Rosenau and Anderson at 

 the United States Hygienic Laboratories at Washington. Their unit of 

 antitoxin is ten times the smallest amount of serum necessary to save the 

 life of a guinea-pig for ninety-six hours, against the official unit of standard 

 toxin. This toxin unit consists of 100 minimal lethal doses of a precipi- 

 tated toxin preserved at the hygienic laboratory of the Public Health 

 and Marine Hospital Service. At the hygienic laboratory at Washington 

 a standard toxin and antitoxin are preserved under special conditions, 

 and standard toxin and antitoxin, arbitrary in their first establishment, 

 are kept constant by being measured against each other from time to 

 time. For details of this standardization the original article in the 

 United States Hygienic Laboratory Bulletin 43, 1903, should be consulted." 



