390 THE SUPPORTING TISSUES. 



Mutton (subcutaneous) 27-31 C. 



Mutton (perirenal) 37-43 C. 



Mutton (epiploic) 36-39 C. 



Man (panniculus adiposus) 15-22 C. 



Man (perirenal) 25 C. 



Dog 20-22.5 



Ox 39 C. 



Bone-marrow of ox 45 C. 



Calf 52 + C. 



Horse 31 + C. 



Pig 40 C. 



Duck 35 C. 



Of special interest is the fact that it is possible to replace the com- 

 mon fats of one animal by those of another, and even by fats which 

 are not found normally in the animal world. If dogs, in which the fats 

 have been removed by starvation, are thus fed with vegetable fats, such 

 as rape-oil, this is subsequently found in the tissues of the animal,. 

 and may be recognized by its low melting-point (23 C.) and the 

 presence of the glyceride of erucic acid. In a similar manner a 

 deposition of mutton tallow may be effected, which begins to melt 

 at about 40 C., while the common fat of dogs melts at 20 C. 



In addition to the fats, small amounts of lecithin, cholesterin, and 

 free fatty acids may also be isolated from adipose tissue. We 

 further find a yellow lipochrome, to which the color of the fat is 

 due. 



Analysis of Adipose Tissue. The material in question is first 

 dried, ground with a little sand, and extracted successively with 

 ether and alcohol. The alcoholic extract is evaporated to dry- 

 ness, the residue washed with water to remove the soluble salts, and 

 is then extracted with ether. The ethereal extracts are united, and 

 the ether is distilled off, when the fats, lecithins, cholesterins, free fatty 

 acids, and the lipochromes remain. The fatty acids are transformed 

 into their salts by adding a slight excess of sodium carbonate, and 

 heating to a temperature of 100 C. The resulting soaps are ex- 

 tracted with water. The insoluble portion is dissolved in ether, the 

 ether is distilled off, and the residue is heated on a water-bath with 

 an alcoholic solution of sodium hydrate, which saponifies the fats.. 

 The resulting material is extracted with ether, which dissolves the 

 cholesterin. The insoluble residue is dissolved in water, and the 

 solution is saturated with carbon dioxide and extracted with strong 

 alcohol. This takes up the soaps and the glycerin. The alcoholic 

 solution is transformed into an aqueous solution, in which the soups 

 are decomposed with a dilute acid. The free fatty acids are thus 

 precipitated, and can then be separated from each other according 

 to the usual methods. 



Aside from adipose tissue, fats are met with in all the organs of 

 the body, but, with the exception of the mammary glands during 

 their functional activity, they are found normally only in traces. 

 Under pathological conditions, however, notable quantities of fat 



