SHEEP 179 



makes it warm. Air is a non-conductor of heat and if this 

 layer of air within the piece of woolen cloth can be kept quiet 

 it will keep the heat of the body inside. This is the function 

 of a garment in regulating body temperature. It keeps heat 

 from leaving the body. 



Shrinking of Wool Garments. — The fact that a wool gar- 

 ment shrinks may be explained as follows: A hair is like a 

 straight smooth rod or tube. But wool is smooth one way 

 and rough the other way. When drawn between the thumb 

 and finger one way the wool fiber feels smooth and the other 

 way it feels rough. This is because it has projections extend- 

 ing outward in one direction. These may be compared with 

 the buds on the branch of a tree in the spring. It is easy 

 to run the hand over the branch one way, but running the hand 

 the other way one strikes the bud obstructions. A hair 

 or cotton fiber is perfectly smooth both ways. 



When a wool garment is washe'd, it is heated in the water. 

 This causes the fibers to expand and in expanding they hook 

 up on each other a Httle farther. Upon cooling the fibers 

 contract again and the garment is that much smaller. When 

 the garment is rubbed, as on a washboard, it makes these 

 points hook up still further and makes the garment shrink 

 worse. When the garment is old and worn so that many of 

 the points or hooks are worn off, it will not shrink so badly. 

 A wool garment made of combing wool, where the fibers are 

 all laid in one direction, will not shrink. 



Yolk. — Most wool is naturally white but contains more or 

 less yolk. This is an oily discharge from the skin to keep 

 the wool fibers soft and glossy. This yolk in the wool collects 

 dirt and dust and frequently gives the sheep a dirty appear- 

 ance. Some breeds have more yolk and look dirtier than 

 others. 



Fleece for Shelter.^ — ^Wool is a good protector from cold. 

 The sheep, therefore, which has a heavy covering of wool is 

 well able to withstand cold weather. This is very valuable 

 to the farmer as he spends less for shelter for sheep. It is 

 also good for the sheep as they can get out in winter and take 

 their normal amount of exercise without suffering from the 

 cold. Even in cold northern countries, a shed open to the 



