MUSCULAR TISSUE 309 



Table XYII shows the composition of various farm animals, 

 expressed for the most part on the same basis as the compo- 

 sition of plants in Table I, except that there is no crude 

 fiber or nitrogen-free extract. 



Table XVII. — Composition of Farm Animals 



In studying the animal it is necessary to know something 

 of the various parts of the body, their general composition, 

 functions, and the reactions taking place in them. The 

 animal is obviously very complex in its structure and only 

 the very general points of physiology can be touched upon. 

 For further information the reader is referred to any good 

 text on animal physiology. (See references at end of chapter). 



220. Bones. — The framework of the body about which 

 all the tissues are grouped, and which serves to give rigidity 

 and afford protection to the more delicate and sensitive 

 parts is composed of bones and is called the skeleton. 

 Chemically bones are composed of protein material called 

 osseous tissue, or ossein, permeated with tricalcium phos- 

 phate and calcium carbonate. The mineral and organic 

 part are present in about equal proportions (Section 169). 

 Bones are hollow to give greater strength to them, and are 

 filled with soft material called marrow, which consists largely 

 of fat and protein. Blood-vessels permeate the bones, and 

 the marrow is supposed to be the source of the red blood 

 corpuscles. Fig. 75 illustrates the appearance of bone tissue 

 under the microscope. 



227. Muscular Tissue. — The flesh of an animal, or muscular 

 tissue is composed usually of bundles of cells called fibers 



