150 TETANUS, MALIGNANT (EDEMA, ETC. 



lation. These symptoms consist in spasms of the muscular 

 system, and generally end in death. The blood and the urine 

 of inoculated animals is toxic to other susceptible animals. 



At the autopsy, apart from the slight inflammatory changes 

 at the point of inoculation, with occasionally the discovery of 

 a few bacilli at that point, no changes are observed in the 

 organs, excepting an intense congestion of the nervous 

 system. 



Bacilli deprived of toxins injected into animals are taken up 

 by the phagocytes. 



Preparation of the tetanus toxin is very easy. A bouillon 

 culture of the Bacillus tetani is grown in an atmosphere of 

 hydrogen at a temperature of 37 C. for from two to four 

 weeks. At the end of that time the culture is filtered 

 through a porcelain filter, and the filtrate is found to contain 

 the tetanin, which is best kept in the dark, and preserved by 

 the addition of 0.5 per cent, of phenol. The power of this 

 toxin, called tetanin, is very great, 5-0 oliTo-o c ' c * ^eing suffi- 

 cient to kill a 15-gram mouse in three to four days. Occa- 

 sionally this toxicity is very much increased, and Burger and 

 Cohn have succeeded in obtaining tetanin, which in doses of 

 c - c ' was fetal to mice. This is b far the most 



FoTTooT o 



powerful poison known; taken in this proportion it would 



mean that about ^ milligram would be fatal to man. Com- 

 pare this with atropine, the fatal dose of which is about 130 

 milligrams, and anhydrous prussic acid, the fatal dose of 

 which is 54 milligrams, and a fair idea of its toxicity will be 

 obtained. 



Tetanin acts on animals only when introduced into the cir- 

 culation; given by the mouth it possesses no poisonous prop- 

 erties. 



The blood of animals dead or affected with tetanus is poi- 

 sonous to other animals in the same way as cultures of the 

 bacillus itself. But it is possible to inoculate animals with 

 doses small enough to produce no fatal effects ; and animals 

 so inoculated are protected from future infection, and their 

 blood and fluid secretions will serve to protect other animals 

 when injected in doses less than the fatal dose. The dis- 



