president's address. 209 



various enteric parasites, especially amongst the lower vertebrates. 

 Scarcely any animal is exempt from some peculiar entozoon of 

 its own ; even birds have their tape-worms : whence do they 

 come ? and what animals act as their intermediate hosts ? There 

 is a little round-worm, Ascaris niffrovenosa, which passes its 

 adult life in streams, but in a less mature condition, inhabits the 

 air-passages of the frog. How many similar "romances of Natu- 

 ral History" remain to reward the researches of a painstaking 

 investigator ? 



As long ago as the year 1675 the presence of bacteria in 

 various parts of man and other animals was made out, and the 

 organisms admirably described by the Dutch microscopist, Leu- 

 wenhoek. And the idea that these bodies were the real cause 

 of diseases was eagerly seized by many pathologists. This idea, 

 in fact, was never entirely lost sight of, and a vast amount of 

 work was done amongst the monads by numerous observers, 

 among whom may be especially mentioned Plenciz, 0. F. Midler, 

 Spallanzani, and Needham. But it was not until a much more 

 recent date that the true fertilising impulse was given, — chiefly 

 by the wonderful researches of Pasteur and Sir Joseph Lister, — 

 to the study of Bacteriology, the first great research of Pasteur 

 resulting in a thorough comprehension of the nature of pehrine, 

 — a silk-worm disease which at one time threatened utterly to 

 destroy the great silk-industry of France ; while the brilliant 

 experiments and observations of Sir Joseph Lister may be said 

 to have almost revolutionized the art and science of Surgery, 

 and to have conferred inestimable benefits upon the wliole human 

 race. The ultimate effect of these researches, continued and 

 supplemented by a host of able workers all the world over, it is 

 impossible as yet to forecast, but it is safe to say that the sister 

 science of Medicine must eventually reap as rich a har\est of 

 good as has already fallen to Surgery. It may be interesting, 

 before attempting to discuss the more recent advances of Bac- 

 teriology to notice briefly the classical research of Pasteur as to 

 the nature of pehrme. 



One of the earliest, if not quite the earliest, of researches into 

 the life-history of morbific microbes was that undertaken by 



