416 TEGUMENTAL SYSTEM. 



Although a part not apparently excitable, in a healthy condi- 

 tion, by either mechanical or chemical stimuli, and although no 

 nerves are traceable into it, yet does it appear to possess some 

 degreee of sensibility, which becomes more manifest under dis- 

 ease ; since the simple introduction of a probe into the cavity 

 of an abscess evidently occasions pain. 



Of Fat. 



Adeps or fat is a concrete oily matter deposited in various 

 parts of the body, apparently more for physical purposes than 

 any important end it can answer in the animal economy. It is 

 contained in a cellular membrane, which only differs from the 

 ordinary kind (the one just described) in its cells being so many 

 little circumscribed or independent cavities {culs-de-sac), by 

 which sage contrivance the fat (which in the living body is a 

 liquid) is prevented from gravitating and collecting about any 

 particular parts. It is this membrane that constitutes the re- 

 sidue (or skin, as it is called) after the fat is melted down by 

 the tallow-chandler. 



Fat exhibits differences not only in different animals, but in 

 different parts of the same species. In some parts of the body 

 it is white ; in others it has a yellowish cast. In general it 

 possesses but little taste or smell : both, however, grow stronger 

 as the animal advances in years. In the living body it exists 

 in the liquid form, and in carnivorous animals it retains much 

 of its oily nature after death : but in graminivorous beasts it con- 

 cretes, on exposure to air, into the white solid substance best 

 known by the name of fat. About the kidneys, particularly 

 in fat animals, adeps is always found deposited in abundance ; 

 assuming here a whiter aspect and a firmer consistence than in 

 other places, for which reason it is commonly called suet. In 

 many parts of the body there is little or no fat ; and when we 

 come to reflect on the nature of their functions, we shall discover 

 that its presence must have proved inconvenient to them : the 

 eyelids, for instance, had they been loaded with fat, could not 

 have moved as they now do ; nor could the penis, so constructed, 

 have answered the purposes for which it was designed. Young- 

 animals have more fat than old, and have it deposited more upon 

 the superficial parts of their body ; in fact, the young of many 

 of the higher animals are enveloped in fat : of this, remarkable 

 examples are found in the infant, the puppy, and the kitten. 

 But it is not so with the foal, the calf, and some few others, 

 which immediately after birth have the power of following their 

 dams, in search after food : fat to them would have proved burden- 

 some, without answering the same useful jnnposes for which 



