202 THE CHEMISTRY OF THE FATIM 



126 lbs. of dry organic matter per 1,000 lbs. live weight 

 per week, and 802 lbs. of this food produced 100 lbs. of 

 increase. When clover chaff took the place of roots, 

 the sheep consumed 164 lbs. of dry organic matter per 

 1,000 lbs. live weight per week, and 1,521 lbs. of dry 

 organic matter was needed to yield 100 lbs. of increase. 

 The use of fibrous or non-fibrous foods had thus a 

 great influence on the total quantity of food demanded 

 by the animal, and on the return obtained from the 

 food consumed. 



It is also obvious from what has gone before that 

 the weight of an animal is by no means a satisfactory 

 datum for determining the quantity of food which -it 

 requires, and that, in fact, a great part of the demand 

 for food is determined by the surface of the animal and 

 not its weight. The fact that small animals require con- 

 siderably more total food per unit of weight than large 

 animals is generally recognised. Feeding standards 

 are thus correct only under certain assumed conditions ; 

 they may, however, be of practical use by serving as 

 the starting point for a more accurate determination 

 of the best ration to be given. 



Production of Wool.— Wool, besides the moisture and 

 dirt which it naturally contains, is made up of three 

 ingredients, suint, fat, and pure wool-hair. The suint 

 is an excretion of the perspiration glands of the skin ; 

 it chiefly consists of a compound of potassium with a 

 nitrogenous organic acid. Suint is soluble in water, 

 and is in great part removed when sheep are washed 

 before shearing. In the case of Merino sheep the 

 suint may amount to more than one-half the weight 

 of the unwashed fleece ; but in the case of ordinary 



