FORMATION OF THE TISSUES FAT. 469 



ramifying on its exterior. When the fat cells exist in any number their arrangement is 

 usually lobular, with an investment of areolar (cellular) tissue, which favours motion 

 and the distribution of the blood-vessels. The vessels enter the interlobular clefts, ramify 

 through their interior, as a solid capillary net-work, occupying the angles formed by con- 

 tiguous sides of the vesicles, and anastomose with one another at the point these angles 

 meet. M. C.] 



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- 

 rate, being dissolved in the latter, at the ordinary temperature of the body. 



[A spontaneous separation of these proximate principles 



mav sometimes be detected within the human fat-vesicle. [Fig. 106. 



The stearine collects in the form of a small star on the 

 inner surface of the membrane (fig. 106,2, 2,2); the elaine 

 occupying the remainder of the vesicle, except where there 

 is an unusually small quantity of fat, when we see a little 

 aqueous fluid interposed between the elaine and the cell- 

 membrane. This offers the best condition for the investi- 

 gation of the membrane. M. C.] 



That the thick oil thus formed does not escape 

 from the fat-cells during life, may be attributed to 



the moistening of their walls by the aqueous fluid Fat Vesicles from an emaci- 

 circulating through the body. In all fixed oils, ated subject; 1,1, the ceii-mem- 

 which are fluid at common temperatures, a portion bra " e; *' 2 ' 2 ' the solid portion 

 of the solid constituents of fat exists : these may be ^ 1LT? 

 separated by exposure to cold, which congeals them, with i t? but not fi i ling ^ C eii.] 

 leaving the Oleine fluid. All these substances are 



regarded by chemists in the light of salts ; being compounds of acids, the 

 Stearic, Margeric, and Oleic with a common base, to which, from its sweetish 

 taste, the name of Glycerine has been given. 



Stearine is the essential constituent of nearly all solid fats, and preponderates in pro- 

 portion to their consistence. It exists largely in mutton-suet; from this it may be obtained 

 by the action of ether, which takes up all the oily matter. It is crystalline, like sperma- 

 ceti; it is not at all greasy between the fingers, and melts at 143. It is insoluble in 

 water, and in cold alcohol and ether; but it dissolves in boiling alcohol or ether, crystal- 

 lizing as it cools. It is composed of 2 proportionals of stearic acid to 1 of glycerine, 

 with two proportionals of water. The Stearic acid (which is the substance of which the 

 stearine candles are composed) may be separated by causing it to combine with a stronger 

 base, such as lime or potash, and then setting it free from this by a stronger acid. Mar- 

 garine exists in small quantity, along with Stearine, with most fats; but it is the princi- 

 pal solid constituent of Human fat, which in this respect resembles olive oil rather than 

 the other animal fats. It corresponds with Stearine in many of its properties; but it is 

 much more soluble in alcohol and ether; and it melts at 118. Its composition is analo- 

 gous (except in the presence of an additional atom of water) to that of stearine, to which 

 indeed it bears a close relation, margaric acid being procurable from stearic acid, by 

 subjecting it to a dry distillation. Oleine exists in small quantity in the various solid 

 fats; but it constitutes the great mass of the liquid fixed oils. The tendency of these to 

 solidification by cold, depends upon the proportion of stearine or margarine they may 

 contain; for oleine itself remains fluid at the zero of Fahrenheit's thermometer. It is 

 soluble in cold ether, from which it can only be separated by the evaporation of the latter. 

 Its composition is analogous to that of margarine; for it consists of 2 proportionals of 

 oleic acid, united with 1 of glycerine and two of water. Glycerine, the base of all the 

 fatty acids, may be obtained from any fatty matter, by saponifying it with an alkaline 

 base, by which this compound is set free. It cannot be obtained in a solid form, but may 

 be brought to the consistence of a thick syrup. It dissolves in water and alcohol; but is 

 insoluble in ether. It has a sweetish taste, whence its name is derived ; and it is remark- 

 able for its solvent powers, which are scarcely inferior to those of water. It is regarded 

 as a hydrated oxyde of a hypothetical base, Glyceryl ; the composition of which is stated 

 by Liebig to be 6 Carbon united with 7 Hydrogen. Glycerin is composed of one propor- 

 40 



