DAIRY INSPECTION 131 
duced. Cows in milk should not be kept in the same 
stable with horses or other animals; they should have a 
separate stable for their exclusive use. There should be 
a special stable for parturition and for cows which are 
not in health. 
(a) Odor of the Air—On entering the stable the 
odor of the air should be noted, since any slight abnor- 
mality will be more perceptible at this time than later, 
when the inspector has become accustomed to the atmos- 
phere. The odor of the air is a good test of the efficiency 
of the ventilation and also of the degree of cleanliness 
of the stable, especially in cold weather when the doors 
and windows are closed and the cows are kept in the 
stable almost continuously. Abnormal odors in stable 
air usually originate from two sources: exhalations from 
the cows and decomposing manure and urine. Condensa- 
tion of moisture on the walls, ceiling, or windows or the 
presence of frost is another indication of defective venti- 
lation. A moist atmosphere assists in the spread of tuber- 
culosis in a stable. The droplets of infected saliva ex- 
pelled by tuberculous cattle in the act of coughing float 
more readily in the stable air when it is saturated with 
moisture than when it is drier. In most instances cattle 
are infected with tuberculosis by the inhalation of in- 
fected air or by the ingestion of infected food or water. 
Insufficient ventilation has the effect of concentrating any 
infection in the air of a stable, while ventilation dilutes it. 
Recent experiments have shown that the harmfulness 
of insufficient ventilation is not due to a deficiency of 
oxygen, an excess of carbon dioxide, or the presence of 
organic poisons in expired air, but to the warmth and 
moisture of the air in unventilated places and to its lack 
of movement. A warm, moist atmosphere has a depress- 
