1891.] on Infections Diseases. 279 



inimical conditions, such as heat, cold, chemicals, &c., and that it is 

 precisely these spores, entering the system by the alimentary canal 

 through food or water, or by the respiratory organs through the air, 

 to which the disease in most instances is due. Further, it has been 

 shown that a trace of the blood of an animal affected with or dead 

 from the disease, when introduced into an abrasion of the skin of 

 man or animal, produces at first a local effect (carbuncle) followed 

 by a general and often fatal infection. But the most important result 

 of the cultivation of the bacillus outside tbe body, in artificial media, 

 was the discovery that if subjected to or grown at abnormally high 

 temperatures, 42° • 5 C, i. e. above the temperature of the animal 

 body, its power to produce fatal disease — that is, its virulence — 

 becomes attenuated, so much so that, while the so-altered bacilli on 

 inoculation into sheep or cattle produce a mild and transitory illness, 

 they nevertheless furnish these animals with immunity against a 

 fatal infection. 



The recognition and identification of the Bacillus anthracis as the 

 true cause of the disease, splenic fever or splenic apoplexy, the 

 knowledge of its characters in the blood and spleen of man and 

 animals, and of its peculiarities in artificial cultures, have enabled 

 us to make a precise diagnosis of the disease, which jjreviously was 

 not always easy or even possible. The knowledge of its forming 

 spores when grown under certain conditions, and of the manner in 

 which experimentally the disease can be reproduced in animals by 

 the bacillus and its spores, has led to a complete understanding of the . 

 means and ways in which the disease spreads both in animals and 

 from them on to man ; and last, but not least, the methods of the 

 protective inoculations first indicated and practised by Pasteur have 

 been solely the result of the studies in the laboratory of the cultures 

 of the Bacillus anthracis, and of experiments with them on living 

 animals. I could add here a number of other diseases — such as 

 glanders, fowl cholera and fowl enteritis, erysipelas, scarlet fever 

 and diphtheria in man, actinomycosis in man and cattle, swine fever 

 and swine erysipelas, grouse disease, symptomatic charbon in cattle, 

 and other diseases of animals — which have been brought to a fairly 

 advanced understanding by methods such as those indicated above ; 

 and hereby not only in the diagnosis and recognition, but also in 

 the treatment and prevention of these disorders, an immense amount 

 of valuable pro^^ress has been achieved. 



[1. Demonstration : lantern slides of anthrax, fowl cholera, fowl 

 enteritis, grouse disease, typhoid, cholera, pneumonia, diphtheria, 

 actinomycosis, scarlatina, and glanders.] 



As examples of the second proposition, viz. that the modern 

 methods of study of disease germs, of their nature and action on 

 living animals, have led to the recognition as communicable diseases 

 of some disorders which previously were not known or even suspected 

 to be of this character, I may mention amongst several the disease 

 known as tuberculosis or consumption, tetanus or lock-jaw, and acute 



