

36 VETERINARY PHYSIOLOGY 



growth in length is stopped. The rate and extent of this 

 growth of the cartilage has an important influence on the 

 growth of the individual. 



(2) CHEMISTRY. The composition of adult boiie is roughly 

 as follows : 



Water, 10 per cent. 

 Solids, 90 per cent. 



Organic, 35 per cent. chiefly collagen. 

 Inorganic, 65 per cent. 

 Calcium phosphate, 51. 

 carbonate, 11. 



fluoride, 0'2. 



Magnesium phosphate, 1. 

 Sodium salts, 1. 



The points to be remembered are the small amount of 

 water, the large amount of inorganic matter, chiefly calcic 

 phosphate, and the nature of the organic matter collagen. 



(B) THE MASTER TISSUES OF THE BODY, MUSCLE 

 AND NERVE 



By means of the epithelial and connective tissues the body 

 is protected, supported, and nourished. It performs purely 

 vegetative functions, but it is not brought into relationship 

 with its environments. By the development of nerve and 

 muscle the surroundings are able to act upon the body, and 

 the body can react upon its surroundings. 



These tissues may therefore be called the Master Tissues, and 

 it is as their servants that all the other tissues functionate. 



So far as the chemical changes in the body are concerned, 

 muscle is more important than nerve, for three reasons 

 First, it is far more bulky, making up something like 42 per 

 cent, of the total weight of the body in man ; second, it is 

 constantly active, for even in sleep the muscles of respiration, 

 circulation, and digestion do not rest; and third, the changes 

 going on in it are very extensive, since its great function is to 

 set free energy from the food. So far as the metabolism of the 

 body is concerned, mtiscle is the master tissue. For muscle we 



