1 4 ELEMENTS OF MAMMALIAN ANATOMY. 



nervous system and making up cartilage and ligaments 



(Fig. n); muscular, composing the greater part of the 



muscular system; and nervous, constitut- 



. ' ing the nervous system (Fig. 97). 



, 



; : ^; The naked eye is unable to distinguish 



the elements of the tissues, but the micro- 

 scope reveals the fact that each kind of 

 FIG. 9. CELLS OF tissue is formed of either cells or fibers 



i C 5 o RTILAGE ' or > as is most frequently the case, a com- 



bination of both. 



The different relative arrangements of these anatomic 

 elements, together with their morphology, permit one to 

 know from what organ any particular section of tissue 

 under consideration has been taken. 



These ultimate units of structure are still further resolved 

 into parts by the chemist, who has shown that they are 

 composed largely of carbon, hydrogen, oxygen, and nitro- 

 gen. Since there can be no energy developed in the body 

 without the disintegration and consequent death of some of 

 the particles composing the millions of tiny cells, it is plain 

 that they must have their losses replaced in order to con- 

 tinue their existence. Therefore a method of preparing the 

 food for the use of the cells, and a way of transporting it 

 to each of them are necessary. 



The former is accomplished by the digestive system, 

 which, through the agency of the salivary, gastric, pan- 

 creatic, and other glands, transforms the food into a special 

 liquid state capable of being absorbed by the millions of 

 minute finger-like villi of the small intestine (Fig. 63). 

 Thence it is transferred by the lacteal vessels and veins to 

 the heart, whence it is conveyed by the arteries to their 

 capillary distribution in the neighborhood of every cell in 

 the body. 



The dead matter or waste material resulting from the 



