870 president's address. 



guinea pig which had died of splenic fever. This suggestion 

 was first made by Dr. B. Sanderson and followed out by Dr. 

 Greenfield, and it has been found that by inoculation in this way 

 cattle become " entirely incapable of contracting splenic fever, 

 remaining free from either constitutional or local manifestations 

 of it." Is it essential that micro-organisms should develop in the 

 blood of the animal in which immunity from further attacks of 

 the disease is to be secured ; or is it possible that the necessary 

 influence upon the system may be exerted by merely chemical 

 products of the growth of that organism in some other medium ? 

 With a view of solving these questions he tells us that Toussaint 

 performed experiments by injecting into the blood of healthy 

 sheep blood taken from an animal affected with splenic fever 

 deprived of Bacillus anthracis. ' If this blood so treated is injected 

 into the circulation of a healthy sheep it produces a true vac- 

 cinating influence, securing immunity from splenic fever, but in 

 order that this change in the constitution of the sheep may be 

 brought about a certain period of time is essential ; if a sheep 

 so vaccinated be inoculated with anthrax within a few days of 

 the operation, it will die of splenic fever, but if not for twelve or 

 fifteen days complete immunity is found to have been produced. 

 ' ' I need hardly remark on the surpassing importance of reseai-ches 

 such as these. In ten years hence some one may be able to record 

 the discovery of the appropriate vaccine for measles, scarlet fever 

 and other acute specific diseases. Bacillus anthracis is morpho- 

 logically identical with an organism met with in infusion of hay 

 termed hay-bacillus. Bacillus anthracis refuses to grow in hay 

 infusion, and hay-bacillus is incapable of growing in the blood 

 of a living animal ; both grow in diluted extract of meat, but 

 their mode of growth differs. Dr. Buchner finding this, carried 

 on experiments to solve the problem of the possibility of chang- 

 ing Bacillus anthracis into hay-bacillus and the converse ; he pro- 

 ceeded to cultivate Bacillus anthracis in extract of meat. For 

 several hundred successive generations ho found that bacillus so 



