ADIPOSE TISSUE. 409 



The fats in question are principally the triglycerides of stearic 

 acid, palmitic acid, and oleic acid. Others, such as the glycerides 

 of capronic acid and valerianic acid, are not constant constituents of 

 adipose tissue, but are met with only exceptionally, and always in 

 very small amounts. In man, a comparatively large amount of 

 olein is found, but it is not so abundant as in certain cold-blooded 

 animals, in which it may form the greater portion of the fat. The 

 quantitative relation between the three forms is by no means con- 

 stant in all parts of the body, so that the melting-point of the fats 

 from different regions may be quite different. It differs, moreover, 

 in diiferent animals. This is shown in the following table, which 

 is taken from Gautier : 



Mutton (subcutaneous) 27-31 C. 



Mutton (perireual) 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 -f C. 



Horse 31 -f 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. General analysis of human fat has given the following results 

 (Jaeckli) : 



Fat from subcutaneous Fat from child Vot _,._, H,-.,-., 

 tissue. three days old. Fat from h P ma - 



Olein 72.1-85.3 per cent. 55.0 per cent. 68.6-90.2 per cent. 



Corresponding amount of 



oleic acid 69.6-81.6 " 52.7 " 65.7-86.4 " 



Palmitic acid 16.9-21.1 " . . 7.8-24.9 " 



Stearic acid 4.9-6.3 " . . 1.5-5.9 



Free acid (calculated as 



oleic acid) 0.19-0.52 " 0.36 " 0.15-0.34 " 



Phosphoric acid (P 2 O 5 ) 0.006-0.007" . . 0.001-0.63 " 



Lecithin 0.07-0.08 " . . 0.01-7.21 " 



Pure cholesterin .... 0.24 " . . ^ 



Non-saponifiable material > 0.34-1. 69 " 



exclusive of cholesterin 0.08 " . . J 



