652 
J. M. WRIGHT. 
are no abrasions, but if it be applied to the latter it must be 
well rubbed in. Infection may take place in the mouth and ali¬ 
mentary canal, through wounds or abrasions, when obtained from 
bridle bits, hitching posts, walls of the stall, manger feed 
troughs, or from infected feeds, such as grain, hay or straw. I 
feel safe, however, in saying that less than ten per cent, of all 
cases of infection take place in the above described manner. 
When it does occur there will invariably be at first a localized 
lesion, which will spread by means of the lymphatics into the 
surrounding parts, which will extend farther and farther until 
it becomes general. The common watering trough is the place 
where animals become infected in a majority of cases. A horse 
is watered one^ or more times each day, when his stomach is 
empty and he is thirsty. Usually under such circumstances he 
will ingest large quantities, which pass at once from the stomach 
into the intestinal tract, where it is absorbed almost immediately 
by two sets of absorbents: 
First, the portal circulation, which carries this infected mat- 
te and po„„ i, into .fc liver, where it for the first time has to 
pass through a capillary system, and where the bacilli have 
their first opportunity to escape from the vessels and gain en¬ 
trance into the tissue spaces and lymphatic vessels, where they 
produce their^ characteristic lesions. Those which fail to es¬ 
cape are emptied into the posterior vena cava and the next cap¬ 
illary system they pass through is in the lungs, where they again 
have the same opportunity as when they passed through the 
liver. 
Second, the mesenteric lymphatic system, which collects and 
pours Its contents into the anterior vena cava through the thoracic 
duct. The infected material having thus found its way into the 
venous circulation, quickly finds its way into the lungs, where it 
for the first time passes through a capillary system and the bacilli 
have an opportunity to escape into the tissue spaces. It will be 
noticed that the early primary lesions are in the parenchyma of 
the lunp and not in the bronchial tubes, which explodes the 
inhalation theory. 
