LECTURE ON BACTERIOLOGY. 
371 
tion. We must avail ourselves of every means of research, and 
patiently endeavor to ascertain what of pure gold there is in this 
new field of study. The subject is a fascinating one, and it seems 
to settle, or at least, open the way of settling, so many hitherto 
difficult questions in pathology, that it has been accepted by 
many without such a basis of facts as every careful investigator 
should demand. Another very extensive and important field 
opened by bacteriology is that of the prevention of disease by in¬ 
oculation of attenuated or modified bacterial matter. 
Pasteur, experimenting with the bacilli of anthrax, found by 
exposing the microbes to a certain temperature higher than that 
most favorable for their development, they lost their virulence to 
such an extent that he could vaccinate sheep without danger ; 
and that animals so vaccinated were, for a given time, rendered 
incapable of contracting anthrax. Various opinions are held 
regarding the value of these experiments at present. You are 
all familiar with the newspaper accounts, at least, of Dr. Ferran’s 
experiments with the cholera inoculation. We are not at the 
present time able to speak with any degree of positiveness regard¬ 
ing the value of this work. 
What is to be the future of the very interesting and fascinat¬ 
ing studies to which I have this afternoon briefly directed your 
attention, no one as yet can determine. It is in the hands of 
ardent students, who are everywhere carrying out new investiga¬ 
tions, and I shall not burden you with my own opinions in regard to 
it. The great question at present to be settled is, whether we are 
about discovering the ultimate cause of many hitherto obscure 
pathological states, or whether these microbes are only bacteria 
of health taking advantage of diminished vitality to develop with 
increased rapidity —whether they are the cause or the scavengers 
of disease. 
Vaccination for Cattle-plague. —The success of Pasteur’s 
method of vaccination for the cattle-plague in India is said to 
have been brilliant. It was used for elephants, cattle, horses 
and sheep. 
