344 A MANUAL OF VETERINARY PHYSIOLOGY 



The water is always in the largest and, excluding the carbo- 

 hydrate, the salts in the smallest proportion. The proportion 

 of protein and fat in the body depends upon the condition of the 

 animal ; the proportion the protein bears to the fat depends not 

 only on the condition, but on the class of animal. The lean ox 

 for a given weight has more nitrogenous substances than fat ; 

 but in the sheep and pig this is reversed. In the fat animal there 

 is always more fat than nitrogenous matters. There are more 

 water and salts in the lean than in the fat animal ; while the ox 

 has more mineral matter than the sheep, and the sheep more 

 than the pig. 



The following table shows the proportion of the chief body 

 tissues of an adult horse weighing 1,100 pounds, and it may be 

 compared with that of a cat : 



Horse. Cat. 



Muscles and tendons 



Bones - 



Skin 



Abdominal viscera 

 Thoracic viscera 



According to Lawes and Gilbert, the following are the relations 

 of these parts in the ox, sheep, and pig for every 100 pounds of 

 living weight : 



The bulk of the body is seen to be represented by the muscles, 

 and these hold half the water and half the protein found in the 

 system. 



Income and Expenditure. — The Income of the body consists of 

 carbon, hydrogen, oxygen, nitrogen, sulphur, phosphorus, salts, 

 and water. These are contained in the food, the oxygen being 

 mainly supplied by the air taken in at the lungs. 



The Expenditure consists of the same elements, which are got 

 rid of by the lungs ; urine, faeces, and skin. 



