258 president's address — section l. 



SECTION L. 



VETERINARY SCIENCE. 



ADDRESS BY THE PRESIDENT : 



Professor Harold A. Woodruff. M.R.C.V.S., M.R.C.S., 



L.R.C.P., 



Professor of Veterinary Pathology in the University of Melbourne. 



THE DEVELOPMENT OF OUR CONCEPTION 

 OF IMMUNITY. 



I have selected this subject on which to address this section for 

 several reasons : it& wide general interest, for it embraces a know- 

 ledge of bacteriology, of many facts of physiology, especially of 

 biochemistry and of physics ; its rapid advance as a science in 

 lecent years, for it must be remembered that it is during the la?t 

 half century that all our exact experimental knowledge in this 

 sphere has been gained; its great fascination for myself personally. 



Immunity in its broadest sense surveys the whole field of the 

 action and reaction between the active agents of disease on the one 

 hand and the animal body on the other; it explains spuptonis, 

 determines treatment, and conditions the issues of infection. Not 

 only is it concerned with infection by bacteria, but with the reac- 

 tions to the introduction into the body of animal cells, bacterial 

 products, enzymes, animal and vegetable poisons, and albuminoid 

 substances. It takes note of the receptivity or non -receptivity of 

 the body on the one hand, and the aggression or virulence of the 

 bactf;rium or parasite on the other. It is well to fix this idea of 

 the duality of the problem at the outset, for immunity connotes 

 not only an organized defence on the part of the animal body, but 

 this in face of an organized aggression on the part of the invading 

 agent. 



