CHAP, in.] ADIPOSE TISSUE AND FAT. 83 



the more solid sebum or sevum suet, tallow. Hunter distinguishes 

 four varieties as to fluidity ; oil, lard, tallow, and spermaceti. The 

 elaine of human fat retains its fluidity at 40 F. Lard melts at 

 86 F. ; tallow at 104 F. Spermaceti is fluid in a heat above 

 115 F., and solid at 112. Oil is elaine with little or no stearine, 

 as the neat's foot oil, obtained from the bones of the ox. In lard, 

 the stearine is in abundance, but the elaine slightly predominates. 

 In tallow and spermaceti there is a predominance of stearine. 



Ultimate Analysis of Fat. Human fat, according to Chevreul, 

 consists of 



Hydrogen 11-416 



Carbon 79-000 



Oxygen 9'584 



100-000 



Distribution. The adipose tissue is found very extensively in 

 the animal kingdom. It is found in larvae as well as in the 

 perfect insect : also in the mollusca. It prevails in all the tribes 

 of the vertebrata. In fish it occurs throughout the body ; but 

 in some, as the cod, whiting, haddock, and all of the ray kind, 

 according to Hunter, it is only met with in the liver. In rep- 

 tiles it exists chiefly in the abdomen. In the frog, toad, &c. it 

 is found in the form of long appendages, like the appendices epi- 

 ploicse, situated on each side of the spine. In birds, it exists chiefly 

 between the peritoneum and abdominal muscles; but there is also 

 a considerable deposit in the bones of the legs, feet, last bones of 

 the wings, and of the tail, especially of the swimming tribes, the 

 oily principle being more abundant than in mammals. Jn mam- 

 malia it is very generally diffused. This class, as a whole, has the 

 greatest quantity under the skin, and about certain of the abdo- 

 minal viscera ; but the hare forms a remarkable exception, it being 

 sometimes difficult to find a particle in its whole body. It usually 

 abounds most in the beginning of winter; and this is especially 

 the case with the hog, and with hybernating animals, which, during 

 their dormant state, absorb it into the system. 



It is ordinarily accumulated in large masses about the kidneys, 

 more particularly in ruminants, where it furnishes the best example 

 of that variety of it termed suet. 



Among mankind many remarkable varieties exist in regard to 

 tliis tissue. Thus, in general, women are fatter than men. The 

 healthy human foetus, after the middle of the period of gestation, 

 accumulates fat in considerable quantities : towards middle age, 

 there is a similar disposition, which has not escaped ordinary 



