lo Veterinary Medicine. 



under a hot sun and with no breeze suffer extensivel}' from in- 

 solation, the temperature of their bodies rising to iio° to 112° 

 Fah. and even higher. Cold is equally potent. With a temper- 

 ature below zero Fah. , the iron bit will freeze the baccal mucous 

 membrane, and cause extensive erosion of the mouth. The cold 

 of salted snow or ice will freeze the feet, causing sloughing of the 

 skin above and around the coronet and shedding of the hoofs, and 

 predisposing to fatal septic infection of the wounds. On the system 

 at large, cold causes retrocession of the blood upon the internal 

 organs, and endangers the occurrence of acute disease in any 

 structure which is already debilitated or otherwise susceptible. 

 The nervous effect of the chilling of the skin is often the unbal- 

 ancing factor which sways the scale in favor of disease, which the 

 system was able to resi.st until this disturbing element was intro- 

 duced. The sudden chill from passing out of the warm barn into 

 the frosty air, from plunging into icy water, from standing in cold 

 rain or sleet, from standing in a draught of cold air especially 

 when perspiring, is a fruitful source of many diseases. In the 

 cow, lying with the udder on a cold stone may be the starting 

 point of mammitis. The effect of sudden chill is well exemplified 

 in the great prevalence of diseases of the respiratory organs at the 

 change of the seasons in spring and autumn when the vicissitudes 

 of temperature are greatest, and the system unprepared by habit, 

 to bear the sudden change. Again it must be noted that expos- 

 ure to cold has a tendency to cause disintegration and solution of 

 the red blood globules, and that certain animals are especially 

 susceptible to this influence. The condition of the atmosphere is 

 often a direct cause of disease as when charged with offensive or 

 irritating gases, the result of decomposition of organic matter, 

 with sewer or cesspool emanations, with deleterious gases from 

 chemical works, telluric sources, or fires. A low state of health, 

 a local irritation in some part of the air passages, or even a speedy 

 asphyxia may be the outcome of such atmospheric conditions. 

 Again the presence of solid particles of a more or less irritant, 

 septic or infecting kind prove the starting point of various 

 diseases. The stone cutters' phthisis, and the sand granule 

 ophthalmia are familiar examples of the irritant, which often acts 

 through the dust of the highway. Of the infecting particles we 

 have the germs of cattle lung plague, of infective ophthalmias, 



