330 PROFESSOR JOSEPH LISTER. 
On the Reiation of Micro-oreanisms to Diszase. By 
JosEPH Lister, F.R.S., Professor of Clinical Surgery 
in King’s College, London.! 
Tue 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 ex- 
hibited. That they were causes of’ putrefaction, or other 
fermentative 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 speculations. Now, 
however, a mass of information has been accumulated re- 
garding 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 pathlo- 
logical 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 Wollstein, in Germany. Though a hard-worked 
general practitioner, Koch has contrived to devote an im- 
mense amount of time and energy to his investigations, 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 
principies to render the coloured objects discernible 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 recognised 
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 human species, as has been lately illustrated 
by the so-called woolsorters’ disease, in the North of 
England. The Bacillus anthracis is a large form of bacte- 
1 An address delivered before the Pathological Section of the British 
Medical Association at Cambridge, August 12th, 1880. 
