On Rabies. 



49 



probable and inconsistent with the facts which were previously well 

 established in this disease. 



The outbreak of the epizooty shortly afterwards subsiding, I was 

 unable to resume experiments till the summer of 1886, when it had 

 become necessary to examine the results said to have been attained 

 by M. Pasteur. His statements, now widely known, communicated to 

 the Academy of Sciences, Paris, from time to time, and published in 

 their 4 Comptes Rendus,' are essentially these : (1) That the virus of 

 rabies and hydrophobia resides in the cerebro-spinal tissues, and is 

 not confined to the salivary glands as hitherto supposed. (2) That 

 by inoculation of this substance upon the brain of another animal by 

 trephining, or by intravenous injection, infection follows infallibly 

 and much more quickly than by subcutaneous inoculation. (3) That 

 the virus from a rabid dog by passing through a series of animals of 

 a different species is modified in virulence ; in monkeys it is attenuated 

 and ultimately lost, in rabbits on the contrary, it is intensified, and 

 after a certain number of inoculations in these animals reaches a 

 maximum, which it maintains unaltered ; these modifications of 

 activity being shown by the duration of the incubation period follow- 

 ing inoculation. (4) That by successive inoculations with virus, the 

 activity of which is progressively diminished either by passing through 

 a series of monkeys, or by the action of dry air upon the spinal cords 

 which contain it, it is possible to confer upon dogs and other animals, 

 together with man, immunity against subsequent infection with the 

 most active lyssic virus. 



In reference to these statements, the first points for investigation 

 were now, the effects produced by inoculation with the cerebro-spinal 

 substance of a rabid animal upon the brain of another, and whether 

 the symptoms stated to be produced thereby were those of infective 

 rabies — lyssa — or, as some contended, merely a neurosis resulting from 

 the injection of foreign matter. 



In the methods adopted in these experiments, I have followed those 

 described by M. Pasteur in his published statements, but for im- 

 parting to me many details of manipulation, I am greatly indebted to 

 Professor Horsley, F.ft.S.,who learned them from M. Pasteur himself 

 in Paris. 



II. Methods of Preparation and Inoculation with Virus. 



The animal from which it is desired to inoculate having died or 

 been killed, a part of the spinal cord is exposed, and the portion 

 desired removed, with precautions against contamination, the requisite 

 instruments, vessels, and other apparatus having been previously 

 sterilised by the recognised methods; the medulla is then carefully 

 ground up to a homogeneous pulp in a glass mortar, and triturated 

 with the proper proportion of sterilised beef-bouillon, as prescribed by 



VOL. XL1II. E 



