ADIPOSE TISSUE. Ixvii 



with opaque and granular contents, but upon minute examination are seen 

 to contain stelliforin acicular crystals, though in some cases their aspect is 

 very faintly granular. It is not improbable that the crystals are formed after 

 death. 



Schwann discovered a nucleus in the fat-cells of the embryo ; the nucleus 

 contains one or two nucleoli, and is attached to the inside of the cell- wall 

 or imbedded in its substance. Although nuclei have rarely been seen "in 

 the cells of well-nourished adipose tissue in after-life, they are readily 

 found when the fat has partially disappeared, and hence it may be inferred 

 that they are always present. This is corroborated by an observation of 

 Bruch, that the eudosmose of water always renders a nucleus apparent. 



The common fat of the human body has been represented as a mixture of 

 a solid fatty substance named "margariu," and a liquid oily substance, 

 " olein ;" the suet or fat of oxen and sheep, on the other hand, consisting 

 chiefly of a second solid principle, " stearin," associated with olein. These 

 substances, margarin, olein, and stearin, are neutral bodies, and themselves 

 compounded of a base named " glycerine " with three fatty acids respectively, 

 the margaric, oleic, and stearic. 



To the above reckoned neutral fats of the animal body a fourth, namely, 

 "palmitin," has now been added ; and they are all considered to be com- 

 pounds of three equivalents of acid, oleic, margaric, stearic, or palmitic, 

 with one equivalent of glycerine, minus six equivalents of water. They 

 have accordingly been named, "triolein," "trimargarin," " tristearin," and 

 " tripalmitin. " The triolein, or liquid fat, holds the other three in solu- 

 tion ; and the varying consistency of animal fats depends on the relative 

 proportion of the solid and liquid ingredients. 



During life the oily matter contained in the cells is liquid ; but the 

 acicular crystalline spots which are sometimes seen after death indicate a 

 partial solidification of one of its constituents. This has been supposed to 

 be the margarin ; but it appears from its chemical relations to be most 

 probably margaric acid. 



The fat being thus contained in closed cells, it will be readily understood 

 why, though liquid or nearly so in the living body, it does not shift its 

 place in obedience to pressure or gravitation, as happens with the water of 

 dropsy and other fluids effused into the interstices of the areolar tissue ; 

 such fluids, being unconfined, of course readily pass from one place to 

 another through the open meshes. 



The areolar tissue connects and surrounds the larger lumps of fat, but 

 forms no special envelope to the smaller clusters ; and although fine fasci- 

 culi and filaments of that tissue pass irregularly over and through the 

 clusters, yet it is probable that the vesicles are held together in these 

 groups mainly by the fine network of capillary vessels distributed to them. 

 In the marrow the connective tissue is very scanty ; indeed, the fat-cells in 

 some parts of the bones are said to be altogether unaccompanied by connec- 

 tive filaments. 



The adipose tissue is copiously supplied with blood-vessels. The larger 

 branches of these pass into the fat-lumps, where they run between the 

 lobules and subdivide, till at length a little artery and vein are sent to each 

 small lobule, dividing into a network of capillary vessels, which not only 

 surrounds the cluster externally, but passes through between the vesicles in 

 all directions, supporting and connecting them. The lymphatics of the fat, 

 if it really possess any, are unknown. Nor have nerves been seen to termi- 

 nate in it, though nerves destined for other textures may pass through it. 



e 2 



