LESS ENERGETIC THAN IN HERBIVORA. 79 



and sheep, it is evident, that, when well supplied with 

 food, their growth in size, their fattening, .must depend 

 on the quantity of vegetable albumen, fibrine, or caseine, 

 which they consume. With free and unimpeded mo- 

 tion and exercise, enough of oxygen is absorbed to con- 

 sume the carbon of the gum, sugar, starch, and of all 

 similar soluble constituents of their food. 



But all this is very differently arranged in our domes- 

 tic animals, when, with an abundant supply of food, we 

 check the processes of cooling and exhalation, as we do 

 when we feed them in stables, where free motion is im- 

 possible. 



The stall-fed animal eats, and reposes merely for di- 

 gestion. It devours in the shape of nitrogenized com- 

 pounds far more food than is required for reproduction, 

 or the supply of waste alone ; and at the same time it 

 eats far more of substances devoid of nitrogen than is 

 necessary merely to support respiration and to keep up 

 animal heat. Want of exercise and diminished cooling 

 are equivalent to a deficient supply of oxygen ; for when 

 these circumstances occur, the animal absorbs much less 

 oxygen than is required to convert into carbonic acid the 

 carbon of the substances destined for respiration. Only 

 a small part of the excess of carbon thus occasioned is 

 expelled from the* body in the horse and ox, in the form 

 of hippuric acid ; and all the remainder is employed in 

 the production of a substance, which, in the normal 

 state, only occurs in small quantity as a constituent of 

 the nerves and brain. This substance is fat. 



In the normal condition, as to exercise and labor, the 



