A BACTERIOLOGICAL STUDY OF EQUINE FISTUL/E. 
343 
can we, by considering the complex anatomy of these parts, 
and, with our knowledge of bacteriology, conceive its being the 
work of micro-organisms in those parts? Hertwig said, “Poll- 
evil may occur without any local injury.” For this and many 
other reasons the researches of science are aroused to study the 
etiology of Poll-evil and fistula from a bacteriological stand¬ 
point, with a view of connecting the disease with bacteria and 
placing it in the category of bacterial diseases. 
The old theory of traumatism, we think, has become too- 
vague and unsatisfactory to satisfy the scientific mind and keep 
pace with the rapid advancement in all other branches of veter¬ 
inary medical science. 
Science has discovered and proved beyond a doubt in the 
last few years that bacteria play a most active part in the etiol¬ 
ogy of a great many diseases, just as there have been wonder¬ 
ful discoveries in the last few years in regard to the causes of 
disease, so there will be still more advancement in that direc¬ 
tion. Therefore, the scientific workers of the present time- 
should feel it their duty, and work as hard to reveal the mys¬ 
teries which surround some of the ills which man and animals 
are heir to. 
In the study of bacteriology we find pathogenic organisms 
getting into the animal system in several ways, and causing 
severe and dangerous trouble—causing abscesses in various 
parts of the animal, also giving rise to diseases known as 
pyaemia and septicaemia. 
Pathogenic organisms are divided into two distinct classes— 
specific and non-specific. 
The specific are always followed by the same disorder under 
whatever circumstances they occur. 
The non-specific ones, according to modes of infection and 
the condition of the tissues, give rise to a variety of diseases_ 
suppuration with its sometime consequences, pyaemia and sep¬ 
ticaemia. It is an open question whether suppuration can occur 
from merely mechanical or chemical irritants, however persist¬ 
ently they act. Ogston was the first to show as a matter of 
