132 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
ing effect upon the animal organism. It decreases the 
working capacity of the muscles and lowers the vaso- 
motor tone. It also causes a congestion of the nasal 
mucous membrane, rendering the animal more suscep- 
tible to respiratory infection. There is also reason to 
believe that metabolism is depressed. A moderately cool 
and moderately dry air in motion is the most healthful 
atmosphere for animal life. 
Ventilation.—The best system of ventilation for dairy stables 
is the one devised by the late Prof. F. H. King. Like other 
systems, it has inlets for the admission of fresh air and outlets 
al 
a 
I 
Ie 
Fie, 9.—Showing on the left how an inlet can be placed in a wall already constructed; 
on the right, how an inlet can be put in a wall being built; and in the centre, an outlet shaft 
with two openings—one just under the ceiling and one a foot above the floor. 
for the removal of impure air, but it has two features which are 
peculiar to it. The inlet flues are bent at a right angle, and 
the outside opening is lower than the inner one, the purpose 
being to prevent the escape of air from the stable through the 
inlets. The outlet flues are built from the floor up and have 
an opening near the floor as well as one near the ceiling, thus 
providing a means of drawing air not only from the upper 
