FAT CELLS; COMPOSITION AND USES OF FAT. 



153 



Fig. 49. 



the cell ; it has been seen, however, in the fat-cells of the embryo. The dia- 

 meter of the greater number of fat-cells, is between l-300th and l-600th of 

 an inch ; but larger and smaller sizes are frequently to be met with. These 

 bodies frequently present themselves in an isolated condition, dispersed among 

 the meshes of Areolar tissue ; but when they are aggregated so as to form 

 masses of fat, they are first collected into little lobular clusters, each of which 

 lias a delicate membranous invest- 

 ment; and these are again united into 

 larger clusters, visible to the naked 

 eye. The aggregation of these often 

 forms masses of considerable size ; 

 the component parts being held toge- 

 ther by Areolar tissue, and also by the 

 blood-vessels which penetrate them, 

 and which ramify minutely among 

 them, forming a capillary network, 

 not only upon the surface of the 

 smallest lobules, but even (it would 

 appear) between their contained fat- 

 cells. In some forms of Adipose tis- 

 sue, such as the marrow of bones, it 



would seem that very little areolar tissue exists, or that it is even entirely 

 absent; and here the capillary plexus forms the principal bond of union be- 

 tween the fat-cells. No lymphatics have been detected in Adipose tissue ; 

 and it would seem to be equally destitute of nerves, excepting such as are 

 passing through it on their way to other textures ; thus accounting for the 

 known i'actof its being insensible, except when those trunks are injured. 



[Fig. 50. 



Cells of Adipose Tissue ; magnified 135 diameters. 



Blood-vessels of Fat; 1, minute flattened fat-lobule, in which the vessels only are represented ; 3, the 

 terminal artery ; 4, the primitive vein ; 5, the fat vesicles of one border of the lobule, separately repre- 

 sented, magnified 100 diameters: 2. plan of the arrangement of the capillaries on the exterior of the 

 vesicles, more highly magnified.] 



185. The consistency of the substance contained in the Fat-vesicles, varies 

 in different animals, according to the proportions of the organic elements, that 

 enter into its composition. These elements are known under the names of 

 Stearine, Margarine, and Oleine: the two former, which are solid when sepa- 



