558 



Prof. W. S. Greenfield. 



[June 17, 



attack, produced by inoculation, exerts any protective influence against 

 a future inoculation with unmodified virus. 



The conclusions arrived at by the experiments made with this 

 object were as follows : — 



1. That anthrax maybe artificially communicated to bovine animals 

 by inoculation with the blood or spleen of the guinea-pig which has 

 died of the disease artificially induced, and that the same result may 

 be attained by inoculation with the Bacillus cmthraeis cultivated from 

 the fluids of a rodent; the disease thus induced being severe, but 

 rarely fatal to previously healthy bovine animals. 



This result had already been attained by Dr. Burd on- Sanderson in 

 some previous experiments, with the details of w T hich I was not ac- 

 quainted when my own experiments were made. 



2. In all the cases thus inoculated, the animals appeared to have 

 acquired either a considerable degree of protection or entire immunity 

 from the results of subsequent inoculation, although much larger 

 doses of the virus were employed. 



Some of my experiments on these subjects have been already 

 published in the Journal of the Royal Agricultural Society. 



In the course of these experiments, I employed on several occasions 

 the Bacillus anthracis artificially cultivated in successive generations 

 in aqueous humour, and finding that the results appeared to vary 

 considerably with the stage of the cultivation, those furthest removed 

 from the original parent source being more frequently inactive, I was 

 led to make a series of observations, of which I now desire to commu- 

 nicate the results. They may be stated as follows : — 



That when the Bacillus anthracis is artificially grown in successive 

 generations in a nutrient fluid (aqueous humour) it maintains its 

 morbific properties through a certain number of generations, but each 

 successive generation becomes less virulent than its predecessor, 

 requiring both a longer time and a larger quantity to exert its morbific 

 action ; and after continuous diminution of virulence, at a certain 

 stage in the successive cultivations, the Bacillus, though maintaining 

 all its morphological characters and its power of growth, becomes 

 completely innocuous even to the most susceptible class of animals. 



It may be added that the modified virus produces forms of modified 

 disease which differ widely from ordinary splenic fever, both in the 

 distribution of the Bacilli and in the nature of the symptoms and 

 pathological appearances. 



It does not appear necessary at the present moment to enter with 

 further detail into the evidence upon the subject of modified inocula- 

 tion and protection from further attack, for this could only be done by 

 a detail of the experiments, which is beyond my present purpose. But 

 it is desirable that I should briefly state the general method employed 

 in the determination of the gradual diminution of virulence by sue- 



