THE STRUCTURE OF THE ELEMENTARY TISSUES: 39 



shrivelled membranes remain behind. By mutual pressure, fat-cells 

 come to assume a polyhedral figure (Fig. 41). 



The ultimate cells are held together by capillary blood-vessels (Fig. 

 42); while the little clusters thus formed are grouped into small masses, 

 and held so, in most cases, by areolar tissue. 



The oily matter contained in the cells is composed chiefly of the com- 

 pounds of fatty acids with glycerin, which are named olein, stearin, and 

 palmitin. 



Development of Adipose Tissue. Fat-cells are developed from 

 connective-tissue corpuscles: in the infra-orbital connective tissue cells 

 may be found exhibiting every intermediate gradation between an ordi- 

 nary branched connective-tissue corpuscle and a mature fat-cell. The 

 process of development is as follows: a few small drops of oil make their 

 appearance in the protoplasm: by their confluence a larger drop is pro- 

 duced (Fig. 43): this gradually increases in size at the expense of the 

 original protoplasm of the cell, which becomes correspondingly dimin- 



Fi. 44. Branched connective-tissue corpuscles, developing into fat-cells. (Klein.) 



ished in quantity till in the mature cell it only forms a thin crescentic 

 film, closely pressed against the cell-wall, and with a nucleus imbedded 

 in its substance (Figs. 43 and 44). 



Under certain circumstances this process may be reversed and fat- 

 cells maybe changed back into connective-tissue corpuscles. (Kolliker, 

 Virchow.) 



Vessels and Nerves. A large number of blood-vessels are found in 

 adipose tissue, which subdivide until each lobule of fat contains a fine 

 mesh work of capillaries ensheathing each individual fat-globule (Fig. 

 42). Although nerve fibres pass through the tissue, no nerves have been 

 demonstrated to terminate in it. 



The Uses of Adipose Tissue. Among the uses of adipose tissue, 

 these are the chief: 



a. It serves as a store of combustible matter which may be re-absorbed 

 into the blood when occasion requires, and, being burnt, may help to 

 preserve the heat of the body. 



b. That part of the fat which is situate 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. 



