390 TETANUS. 



Summary. In view of all the facts available we must 

 thus look on tetanus as caused by the B. tetani. The 

 bacillus gains entrance to the body through wounds or 

 abrasions, and, multiplying locally, produces poisons which 

 diffuse into the tissues and have an elective action as stimu- 

 lants especially of the spinal cord. The chemical composi- 

 tion of these poisons is not yet fully known. The enormous 

 potency of such poisons explains how, even in a fatal case, 

 extreme smallness of the wound and difficulty in isolating 

 the bacillus do not detract from the theory that the latter 

 is the cause of the disease. 



Immunity against Tetanus. Antitetanic Serum. 

 The artificial immunisation of animals against tetanus has 

 received much attention. The most complete study of the 

 question is found in the work of Behring and Kitasato in 

 Germany, and of Tizzoni and Cattani in Italy. The former 

 observers found that such an immunity could be conferred 

 by the injection of very small and progressively increasing 

 doses of the tetanus toxine. The degree of immunity 

 attained, however, was not high. More successful was the 

 method of accompanying the early injections of such 

 toxine with the subcutaneous introduction of small doses 

 of iodine terchloride. Tizzoni and Cattani have also used 

 the method of administering progressively increasing doses 

 of living cultures attenuated in various ways, e.g., by heat. 

 By any of these methods susceptible animals can rapidly 

 acquire great immunity, not only against many times the 

 fatal dose of tetanic toxine, but also against injections of 

 the living bacilli. The degree of immunisation acquired 

 by an animal remains in existence for several months. Not 

 only so, but the injection of the serum of such immune 

 animals can protect susceptible animals against the subse- 

 quent infection with a fatal dose of tetanus bacilli or toxine. 

 Further, if injected subsequently to such infection, the 

 serum can in certain cases prevent a fatal result, even when 

 symptoms have begun to appear. The degree of success 

 attained depends, however, on the shortness of the time 

 which has elapsed between the infection with the bacilli 



