ON MURRAIN, OR THE VESICULAR EPIZOOTIC. 39 
mals. The best and most efficient mode of introducing fresh air 
has been the subject of much writing and discussion. The great 
desideratum is, to obtain a sufficiently rapid change of air, and 
yet to avoid draughts. Both these ends seem attainable by 
having one set of apertures for the entrance of air made in the 
lower part of the building, within a foot or two of the ground, 
and another set for its exit made at a convenient height above 
the eaves, and on the opposite side of the house from where the 
air entered. The lower set of apertures should be covered by 
wire-gauze or coarse haircloth, and, if necessary, ventilating 
boards, which can be regulated at pleasure, may be placed 
with the gauze. To prevent currents, similar boards should also 
be placed over the upper set of apertures. The principles here 
laid down are similar to those recommended by Dr. Arnott for 
the ventilation of rooms and dwelling-houses, and their applica- 
tion is at once simple and efficacious. An abundant supply of 
pure air, and a frequent renewal of that air, besides maintaining 
the system in a vigorous and healthy state, and preventing the 
predisposition to murrain, is also a most potent means of de- 
stroying the action of the exciting cause. It dilutes freely and 
fully the noxious and contagious principles evolved from the 
bodies of the sick, and by this dilution deprives the specific 
poison of its power of affecting the sound stock. But a judi- 
cious system of ventilation, in addition to its pow'er of prevent- 
ing disease, also carries with it a curative action, exercising on 
the bodies of all animals, whether healthy or diseased, a tonic 
power ; and whffst it protects the sound animal from the assaults 
of the disease, enables the sick one to bear up against the 
attack, prevents untoward complications, and wards off that 
typhoid fever so frequently an attendant on the epizootic affec- 
tions of cattle. 
The temperature of the atmosphere should also be made the 
subject of attention. Although a certain amount of warmth is 
necessary to the health and well-being of animals, and materially 
promotes their condition, still an overheated atmosphere is very 
injurious, and, when breathed for a long time continuously, acts 
as a powerfully depressing agent, and hence becomes an active 
predisposing cause of disease. The bad effects which would 
otherwise invariably follow from living in a close overheated 
atmosphere are, in part at least, obviated by a beautiful and 
beneficent arrangement, by which “ the animal body being 
naturally much warmer than the surrounding air, operates as a 
ventilator for itself, by the same consummate adaptation of pneu- 
matic laws as that which supplies a flame or fire with a con- 
tinued current of fresh air.” The temperature of houses in- 
habited by animals should never be allowed to rise above 60° F. ; 
