Microblc Diseases Individually Considered. 293 



3 cc. of 1 per cent solution of trichloride of iodine, 

 the latter injection being repeated every twenty-four 

 hours until the rabbit had received in all 0-15 grams 

 of the trichloride. If, after fourteen, eighteen, twenty- 

 five days, 2 cc. of the \irulent filtrate, or 2 to 3 cc. of 

 virulent bouillon culture, be injected, the tetanic 

 symptoms which supervene disappear in a few days 

 and the animal can then receive an injection of 5 cc. 

 of virulent culture without manifesting any symp- 

 toms. The rabbit is therefore vaccinated; but this 

 process is inconstant, and sixty per cent of the rabbits 

 do not obtain immunity. The mouse and guinea pig 

 do not obtain it at all. Now, the serum and blood 

 of these vaccinated rabbits possess the very interest- 

 ing property of destroying the toxine; they are toxin- 

 icidal. A mixture, twenty-four hours old, of 1 cc. of 

 a virulent culture with 5 cc. of this serum can be in- 

 jected with impunity to mice. It is even possible 

 by means of this serum to check the disease experi- 

 mentally developed in the mouse. Further, the in- 

 jection of 0-2 to 0-5 cc. of this serum into the peri- 

 toneum of the mouse confers an immunity of from 

 forty to fifty days' duration. 



Tizzoni and Cattani have obtained immunity in the 

 dog and pigeon by the injection of progressive doses 

 of cultures of gradually increasing virulence. The 

 serum of the dog, thus vaccinated, is toxinicidal and 

 confers immunity on the dog and on the mouse but 

 not on the rabbit or guinea pig, and does not check 

 the disease when already established. These authors 

 have isolated and obtained in the dry state the tox- 

 inicidal product of the serum {antitoxin); they appear 



