Animal Heat. 239 



heat, which is thereby lost from the body. We see here the 

 advantage of clipping working horses in the winter. The 

 effect of clipping on the body temperature has been ob- 

 served by Siedamgrotzky. He found that the tempera- 

 ture of horses rose after clipping, and fell about the fifth 

 day to normal. This rise in body temperature is remark- 

 able, and is possibly explained by supposing that an in- 

 creased production of heat was set up by cooling the 

 surface. 



The Amount of Heat produced in the body is spoken of 

 as so many calories produced per hour per kilogramme 

 (2*2 lbs.) of body weight, and the hour-calorie-kilogramme 

 for animals is given by Colin as 2'1 for the horse ; sheep, 

 2-6 ; man, 2*3 ; sparrow, 3*2. The smaller the animal the 

 greater the production of body heat. 



The quantity of heat developed by a horse in a day is 

 given by Colin as capable of raising by 1-8° Fahr. 4,550 

 gallons of water, or it will raise from freezing to boiling 

 point a little more than 44 gallons of water. 



The Regulation of the Body Temperature is no doubt largely 

 produced by the skin. The respiratory passages also assist, 

 which is the explanation of the panting observed in the dog, 

 in which animal the skin practically does not sweat ; and the 

 remark respecting panting will apply to cattle, especially 

 those in show condition : here the increased respiratory 

 movement robs the body of heat by warming a larger volume 

 of air. It is more than probable that heat production may 

 be increased or controlled by impressions from the nervous 

 system ; section of the sympathetic in the neck causes a 

 rise in temperature on the same side, and division of the 

 spinal cord causes a fall in temperature ; but both a rise 

 and fall may be produced by the action of the nerves on 

 the bloo Ivessels, causing dilatation of them with increased 

 flow of blood into the skin, and consequently greater loss 

 of heat ; or constriction of the vessels of the skin, followed 

 by a diminished loss of heat. 



A loss of heat is also produced by conversion into vapour 

 of the sweat of an active skin, the secretion of which is 



