The Growth of Veterinanj Pathology. 
809 
logical research has discovei’ed new diseases, has revolutionised the 
views formerly held regarding many others, and is now pointing the 
way to methods of cure and prevention that were scarcely dreamt of 
two decades ago. 
As a first illustration we may take Tuberculosis. Twenty years 
ago this disease was generally ascribed to some mysterious quality of 
the tissues — a quality peculiar to certain breeds and individuals, and 
one in consequence of which almost any irritant, such as would in 
other individuals excite merely a passing inflammation, might serve 
to light up a destructive process, capable of spreading throughout the 
whole body. That it was contagious or infectious was not generally 
admitted by veterinary surgeons, in this country at any rate, but it 
was believed that it might be generated in various ways, such as by 
close breeding, exposure, or improper feeding. At the present day, 
on the other hand, we have no need to speculate regarding the cause 
of tuberculosis. It has been proved, beyond the possibility of doubt, 
that tuberculosis is caused by the introduction into the system of a 
minute vegetable parasite or germ, and the disease has now to be 
classed with the contagious maladies. We know further that tuber- 
culosis is identical with the disease termed consumption in the human 
subject, and we have to reckon with the possibility of the disease being 
transmitted between ourselves and our domesticated animals. 
Anthrax affords another example of the revolution that has been 
effected in our notions regarding the cause of important diseases. In 
text-books published less than Wenty years ago anthrax is vaguely 
described as a disease in which “ there is a sudden change in the 
physical characters and physiological properties of the blood.” It 
was believed that it originated spontaneously, and that geographical, 
climatic, and dietetic conditions played an important rule in its pro- 
duction. Furthermore, it was regarded as a disease that assumed 
many forms, the two commonest in cattle being splenic fever and 
black-quarter. 
Every one of these notions has had to be discarded. Anthrax, 
like tuberculosis, is now known to be a disease that owns but one 
cause, viz. the entrance into the body of a vegetable organism— the 
anthrax bacillus. The so-called black-quarter, once regarded as a 
mere variety or modified form of anthrax, is now known to be a per- 
fectly distinct disease, caused by another bacillus, which, broadly 
speaking, is as different from the anthrax bacillus as a sheep is from 
a goat. 
Glanders, again, is a disease regarding the cause of which we have 
acquired further assurance only within the last few years. It, too, was 
formerly regarded as a disease that had various causes, and that 
sometimes originated spontaneously, but it is now known that every 
case of glanders is due to infection with a germ derived from some 
antecedent case of the disease. 
But, perhaps, the disease regarding whose nature and cause the 
most complete change of opinion has been effected within the last 
few years is Tetanus or Lock-jaw — a disease which, from the suffer- 
ing that it causes, and from its great fatality, ranks as one of the 
