XXX VIII THE ROYAL SOCIETY OF CANADA 
BACTERIOLOGY. 
At the beginning of the period I am dealing with scientific men 
were still to be found who believed in the spontaneous generation of 
living creatures of small size like bacteria and infusoria, and this in 
spite of the fact that Pasteur, Tyndall and others had shown that with 
proper precautions nutritive infusions could be kept perfectly free 
from fermentative and putrefactive changes caused by the presence 
of such organisms. So impressed was Lister with the belief that such 
organisms were responsible for unfavourable conditions in surgical 
wounds that he conceived his antiseptic methods, by no means, at 
that time generally adopted, but destined to bring about a new era 
in surgery. This period saw the beginning of the science of Bacteri- 
ology, the development of which has not only revolutionized con- 
ceptions as to the cause and treatment of many diseases, but has proved 
of inestimable service in agricultural and other economic directions. 
The botanist Cohn had, it is true, already advanced the study of these 
simple plants from a botanical point of view, but little was known as 
to their functions. One of them had already been recognized as the 
constant accompaniment of Anthrax, a disease of cattle and horses; 
but it was not until 1876 that Koch definitely proved that this bacillus 
was the cause of the disease. This point of vantage once obtained 
and the methods of isolation and cultivation of bacteria outside of the 
body and in experimental animals developed, the succeeding years 
soon added to the list of known pathogenic bacteria, the causes of 
cholera, typhoid, diphtheria, and numerous other diseases. 
And these investigations necessarily led to others, the study of the 
causes of the immunity enjoyed after recovery from an infectious disease. 
Pasteur had already shown in 1880 that the virulence of the 
anthrax bacillus could be artificially lessened and that (a phenomenon 
resembling the efficacy of vaccination against small-pox) with the aid 
of the attenuated virus, immunity against the virulent form could be 
conferred upon animals. Further it was learned that the real danger 
of pathogenic bacteria consists in the formation of poisons, the so- 
called toxins, in the infected animal and that the latter has, in virtue 
of qualities inherent in its blood, the power of producing antagonistic 
substances, the so-called antitoxins, which may persist in the blood 
after recovery. 
Behring was the first to realize that antitoxins produced experi- 
mentally in one animal by accustoming it to gradually increasing doses 
of a toxin could be employed for the prevention and cure of disease 
by introducing the immune serum into the body. And it is to this 
discovery that the death-rate in diphtheria has been so enormously 
reduced by the employment of diphtheria antitoxin. 
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