22 HITCHCOCK'S ANATOMY 



period of augmentation, another of perfection, another of de- 

 cline, and, finally, one of cessation. So long as vitality can use 

 chemical and physical agencies for building up the system, 

 they tend to its preservation, but, when life ceases, they tend 

 to its destruction, not, as is generally thought, because the 

 vital principle has not the power of resisting these agencies, 

 but because it can no longer turn them into the channel for pre- 

 serving the system. 



PRIMARY TISSUES. 

 The chief mass of the animal system is made up of the ele- 

 mentary forms that have been described, variously combined 

 so as to form plexuses and webs > which are called primary 

 tissues by some, and compound tissues by others. They are 

 differently classified by different writers. The arrangement 

 which follows is that of Professor W. B. Carpenter : 



1. Simple Fibrous Tissues, 



68. White and Yellow Fibrous Tissues.— This embraces 

 the white and yellow fibrous tissues, as well as the areolar or 

 connective tissue of other writers. The white fibers are from 

 isVffoth to the ooH'ooth of an inch in diameter, and form the 

 tendons, ligaments, and fibrous membranes. (Fig- 13.) The 



Fig 13 Fig. 14 



67. Give the four different periods in the life of cells, 

 ©f white and yellow fibrous tissues. 



6S. Give the size of the fibers 



