156 
SOCIETY MEETINGS. 
so extensive that no disease deserves more attention. It exists 
in the lower animals to a greater extent than most people sus¬ 
pect, the dairy cow being most predisposed. Accessory causes 
of the disease are : (i) Hereditary predisposition ; (2) dark, damp, 
ill-ventilated stables. The symptoms are not always present, 
and we rely nearly wholly on the tuberculin test. The char¬ 
acteristic lesion of tuberculosis is the miliary tubercle, which 
consists of three forms of cells—giant, epithelial cells, and leu¬ 
cocytes ; the tubercles are devoid of blood vessels. The origin 
of the various constituents of the tubercle and their relation to 
the bacilli : The fixed cells of the tissue first show signs of 
change. They are induced to proliferate by the bacilli. The 
nuclei of these cells show karyokinetic figures, and both the 
giant and epithelial cells result from these changes. 
The neighboring blood vessels are affected by the virus and 
from them an emigration of leucocytes occurs. This transfor¬ 
mation is rapid or slow, according to the number of bacilli pres¬ 
ent. Changes in the tubercle : Caseous necrosis, or necrosis, 
and fatty degeneration of the structures. 
Fibrous transformation occurs in chronic cases and when the 
bacilli are few. Softening is the result of caseation and ends in 
a cavity or ulcer, or it may accumulate without softening and 
undergo calcareous infiltration. 
Post-mortem lesions may be found in nearly any organ of 
the body, the glands at the bifurcation of the trachea being 
especially predisposed. 
The bacilli may be passed from a diseased animal from the 
discharges from the nose and mouth, discharges from the bowels, 
in milk, etc. It is transmitted from animals to man principally 
by the milk ; also by the meat if not well cooked. 
Infection of cattle may occur: Nine-tenths by inhaling the 
tubercle bacilli dried and suspended in air, one-tenth by the 
food infected. Rarely through copulation. From 1 to 2 per 
cent, of calves may be born with tuberculosis. 
Butter and cheese factories are great sources of danger, the 
milk being all mixed and each patron taking home his share of 
the skim milk or whey and feeding his calves. 
To keep clear of tuberculosis : 
1. Do not buy any stock that has not been tested. 2. Keep 
outside animals out of your stables. 3. Do not allow consump¬ 
tives to care for your stock. 4. Keep the stables well lighted,, 
ventilated and drained. 
Sanitary precautions to observe if tuberculosis is present: 
