AREOLAR TISSUE. 



41 



and irregular shape, to which the term lobules is commonly 

 applied. Under the microscope it is found to consist essentially 



FIG. 11. 



A small cluster of fat-cells ; magnified 150 diameters (Sharpey). 



of little vesicles or cells about ^J tn or TOO^ f an i llcn m 

 diameter, each composed of a structureless and colorless mem- 

 brane or bag, filled with fatty matter, which is liquid during 

 life, but in part solidified after death. A nucleus is always 

 present in some part or other of the cell-wall ; but in the ordi- 

 nary condition of the cell it is not easily or always visible. 

 The ultimate cells are held together by capillary bloodvessels ; 

 while the little clusters thus formed are grouped into small 

 masses, and held so, in most cases, by areolar tissue. The only 

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

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

 stearin, and palmitin. 



It is doubtful whether lymphatics or nerves are supplied 

 to fat, although both pass through it on their way to other 

 structures. 



Among the uses of fat, these seem to be the chief: 



1. It serves as a store of combustible matter which may be 

 reabsorbed into the blood when occasion requires, and being 

 burnt, may help to preserve the heat of the body. 



2. 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 sur- 

 face. 



3. As a packing material, fat serves very admirably to fill 

 up spaces, to form a soft and yielding yet elastic material 

 wherewith to wrap tender and delicate structures, or form a 

 bed with like qualities on which such structures may lie unen- 

 dangered by pressure. As good examples of situations in which 



