ON THE RELATIONS OF MICRO-ORGANISMS 
TO DISEASE 
An Address delivered before the Pathological Section of the British Medical Association 
at Cambridge, August 12, 1880. 
[Quarterly Journal of Microscopical Science, April 1881.] 
THE relation of micro-organisms to disease is a subject of vast extent and 
importance. If we compare the present state of knowledge regarding it with 
that of twenty years ago, we are astonished at the progress which has been 
made in the interval. At that time bacteria were little more than scientific 
curiosities ; whether they were animal or vegetable few people knew or cared, 
but most regarded them as animals on account of the active movements which 
they often exhibited. That they were causes of putrefaction, or other fermenta- 
tive changes, was a thing scarcely thought of; and the notion that they had 
special relations to disease would have been regarded as the wildest of specula- 
tions.._ Now, however, a mass of information has been accumulated regarding 
all these points, of which it would be hopeless for me to attempt to give even 
a brief sketch in the time at my disposal, and all that I can do is to present 
to the pathological section a few examples illustrating the progress which is 
being made in this department of research. 
First, I will mention some examples of the labours of Dr. Koch, of Woll- 
stein, in Germany. Though a hard-worked general practitioner, Koch has 
contrived to devote an immense amount of time and energy to his investiga- 
tions ; and by a combination of well-planned experiments, ingenious methods 
of staining bacteria out of proportion to the tissues among which they lie, 
a beautiful adaptation of optical principles to render the coloured objects dis- 
cernible by the human eye, and, further, by a most successful application of 
micro-photography, he has succeeded in demonstrating the presence of these 
minute organisms in a manner never before attained. 
The Bacillus anthracis is now universally recognized among pathologists as the 
cause of splenic fever, so fatal among cattle in this and other countries and capable 
of being communicated to various other animals, and, among the rest, to the 
’ The bacterium of splenic fever (anthrax) was seen and described by Rayer and Davaine as early 
as 1850; but little was done during the next ten years towards establishing the true relations between 
the micro-organism and the disease. See Recherches expevimentales sur la Maladie Charbonneuse, par 
H. Toussaint. Paris: Asselin & Cie. 
Cee 
