16 



ADVANCED PHYSIOLOGY 



FIG. 8. MUS- 

 CLE CELLS 

 FROM THE 



in bundles, as in tendons (Fig. 6); or in confused masses running 

 in all directions, as in the soft mass of connective tissue 

 beneath the skin; Fig. 7. But in each a few 

 genuine cells can be seen, and a study of the 

 growth of connective tissue shows that the fibres 

 are really produced by the cells. 



Muscle tissue consists of fibres, sometimes 

 tapering at the ends; Fig. 8. When the muscle 

 contracts, these fibres diminish in length and 

 thicken in the middle. Such a fibre is some- 

 times a single muscle cell, and sometimes several 

 cells fused together, but in any case it is cellular. 

 Gland cells are frequently cylindrical, some- 

 times nearly spherical; Fig. 9. The material 

 they secrete collects in them and is later ex- 

 pelled, either continuously, as in some glands, 

 or at intervals, as in others. 

 WALL OF THE Blood consists of many cells, called blood 

 INTESTINE corpuscles, floating in a liquid; Fig. 10. This 

 liquid is not formed like the mass of 

 material separating the cells in cartilage 

 and in bone, since it is not produced by 

 the blood cells themselves. 



Nerve cells differ widely in shape; some 

 are nearly round, some are very long and 

 some are irregular in outline. A com- 

 mon type has an angular body with a 

 few much-branched prominences extend- 

 ing from the corners; Fig. 11. 



Fat cells are like some of the other cells 

 of the body, but pick up bits of fat from 

 showingTtTtheceiisthat the blood, holding it until it is wanted; 

 secrete, at 6 the duct that Fig. 12. These cells incidentally form 



carries away the secretion < i i r 



and at c the blood ves- a sort of cushion or packing for some 



aels supplying the gland. of the Soft parts of the body. 



FIG. 9 A PORTION OF A 



GLAND 



