324 A STUDY OF FARM ANIMALS 



ment, with their edges fitting closely together, the fiber will 

 be smooth and lustrous, a quality especially noticeable in 

 the long, coarse wools, like those of the Cotswold and Lin- 

 coln. The qualities of rigidity or pliability of wool are due 

 to the scales. If they fit over each other loosely, with 

 prominent projecting points, they felt most easily, and will 

 be soft and pliable, while, if they fit close, with little over- 

 lapping, as in hair, they will have little or no felting quality 

 and will be stiff and resistant. 



The cortex of wool consists of a quantity of more or less 

 long, straight cells, united to give the fiber its round form. 

 From the cortex the fiber derives its tensile strength and 

 elasticity. If the fiber is very fine, the cells of the cortex 

 are more or less uneven in length and grouping, so that it 

 takes on a wavy appearance or what is commonly termed 

 crimp. This property is most marked with Merino wool, 

 where we may find 25 crimps to the inch, while it is least 

 seen in the long wools, where only 2 or 3 crimps 

 usually occur. The degree of crimp adds much to the 

 elasticity and spinning quality of the wool. 



The medulla, or pith, of wool consists of round cells in 

 the center of the cortex. Sometimes the medulla occupies 

 from one fourth to one third of the diameter of the fiber, 

 and again it may be barely present, or even not at all. Pig- 

 ment, or coloring matter, is frequently found in this part, 

 and is especially present in the medulla and cortex of colored 

 wools. The medulla acts as a tube for transferring nutrition 

 the length of the fiber, and also as a medium for introducing 

 dyes and so artificially coloring the wool. 



Some features of wool that are important in the trade 

 should receive brief consideration here. 



The fleece refers to the entire covering of wool on the 

 sheep or the same removed and tied in a bundle in the wool 

 warehouse. The fleece differs in its length and quality 

 according to the part of the animal from which it comes. The 



