38 CELL DIFFERENTIATION AND THE ELEMENTARY TISSUES 



is as follows: a few small drops of oil make their appearance in the proto- 

 plasm, and by their confluence a larger drop is produced, figure 45. This 

 gradually increases in size at the expense of the original protoplasm of the 

 cell, which becomes correspondingly diminished in quantity till in the mature 

 cell it forms only a thin crescentic film with a nucleus closely pressed against 

 the cell-wall. Under certain circumstances this process may be reversed, 



A large number of blood-vessels are developed in adipose tissue, which 

 subdivide until each lobule of fat contains a fine meshwork of capillaries 

 ensheathing each individual fat-globule, figure 44. 



Adipose tissue serves as a storehouse of combustible matter which may 

 be reabsorbed into the blood when occasion requires, and, being used up 

 in the metabolism of the tissues, may help to preserve the heat of the body. 

 That part of the fat which is situated beneath the skin must, by its want of 

 conducting power, assist in preventing undue waste of the heat of the body 

 by escape from the surface. 



CARTILAGE. 



All kinds of cartilage are composed of cells embedded in a substance 

 called the matrix. The apparent differences of structure met with in the 

 various kinds of cartilage are more due to differences in the character of 

 the matrix than of the cells. With the exception of the articular variety, 



FIG. 47. Hyaline Articular Cartilage (Human). The cell bodies entirely fill the spaces in 

 the matrix. X 340 diams. (Schafer.) 



cartilage is invested by a thin but tough firm fibrous membrane called the 

 perichondrium. 



Cartilage exists in three different forms in the human body, viz., hyaline 

 cartilage, yellow elastic cartilage, and white fibro-cartilage. 



Hyaline Cartilage. This variety of cartilage is met with largely in 



