IMMUNITY-GIVING SUBSTANCES. 147 



guinea-pig ; three weeks later inject 0.2 c.c. of a culture 

 in bouillon containing iodine trichloride in the proportion 

 of 1 : 5500. 



(3) By the metabolic products of the diphtheria bacillus 

 in the living body. In the pleural cavities of guiuea-pigs 

 killed by inoculation with the germ there is often a reddish, 

 germ-free transudate; 10 c.c. to 15 c.c. of this kills guinea- 

 pigs ; small amounts give immunity. 



(4) By iuoculatiug with the virulent germ and arresting 

 the growth of the same with iodine trichloride, gold-sodium 

 chloride, uaphthylamine, or carbolic acid. Of eight guinea- 

 pigs, each of which was inoculated with 0.3 c.c. of a viru- 

 lent culture, two, which were not treated, died within 

 twenty-four hours ; four, which had — two each — a 1 per 

 cent, and a 2 per cent, solution of iodine trichloride injected 

 immediately and at tlie place of inoculation, recovered ; of 

 two which had the same treatment six hours after the 

 inoculation, one died after four days. 



(5) By peroxide of hydrogen in diluted sulphuric acid. 

 Guiuea-pigs bear from 1 :4000 to 1 : 2500 ; mice, 1 : 2000 

 to 1:800; rabbits, less than 1 : 1500 of this substance 

 per body-weight. Injections of this solution before inocu- 

 lation give more or less immunity, or, rather, increase the 

 resistance to the disease ; given after inoculation it hastens 

 death. 



None of these methods are applicable to the prevention 

 or treatment of the disease in man. 



TizzoNi and Cattani have reviewed the above state- 

 ments in so far as they refer to tetanus. These experi- 

 menters find that the addition of an equal volume of 

 either a 2 per cent, solution of fresh chlorine water or 

 iodine trichloride, or a 5 percent, solution of phenylic acid 

 to the poisonous, filtered tetanus culture destroys the tox- 

 icity of the same ; but they state that the injection of these 

 substances into animals either before or after inoculation 

 with the germ has no effect upon the development or course 

 of the disease. 



However, they do find that the blood-serum of an ani- 

 mal which is immune will protect against either the 



