THE FILTERABLE MICROBES 373 



out contamination, should be injected into the brain of guinea- 

 pigs and rabbits and the effects observed. This last test caF 

 ried out by an experienced observer is the most trustworthy 

 of all. 



The Pasteur treatment of rabies is designed to induce immu- 

 nity after the person has been bitten and before the disease has had 

 time to develop. Pasteur 1 first demonstrated the possibility of 

 this by experimental work on dogs, and the subsequent use of 

 the method in man has been remarkably successful and the dis- 

 ease is practically always prevented if the treatment is begun 

 directly after infliction of the infecting wound. The first essen- 

 tial is thorough cauterization of the wound, best with concentrated 

 nitric acid under anesthesia. The patient is then injected sub- 

 cutaneously with emulsions of the spinal cords which have been 

 removed from rabbits dying of rabies after inoculation with the 

 fixed virus, and which have been dried by hanging in bottles 

 over caustic soda for some time. The first injection is prepared 

 from cords hung for 14 and 13 days, the second from cords hung 

 1 2 and 1 1 days, and so on until the three-day cord is reached on 

 the seventh or eighth day of the treatment. The series from 

 five-day down to three-day cords is then repeated several times, 

 the whole treatment lasting about 21 days. The course of treat- 

 ment is varied somewhat according to the urgency of the case and 

 the severity of the wounds inflicted. It is most effectively carried 

 out at special Pasteur institutes devoted to this work, but the 

 material for injection may be shipped for some distance when 

 necessary. 



The Virus of Hog Cholera. Dorset, Bolton and McBryde, 

 continuing the investigations of de Schweinitz, demonstrated in 

 1905 the presence of a filterable agent in the blood of hogs suffering 

 from hog cholera, capable of causing the disease upon injection 

 into healthy animals. It passes through the Chamberland "B" 

 and "F" filters. It leaves the body in the urine and probably 

 also in other excretions, and seems to enter the new victim with 



1 Vallery-Radot, The Life of Pasteur, 1911, Vol. II, p. 188. 



