86 PHILOSOPHY 01' ZOOLOGY. 



pine, to assist in rolling up the body and moving the spines, 

 and in birds, in the erection of their feathers. In man, it 

 can scarcely be said to exist, unless in the upper parts, 

 where cutaneous muscles may be observed, destined for 

 moving the skin of the face, cheeks and head. In the 

 skin of the frog, the only cutaneous muscles which can be 

 observed, are seated under the throat ; the skin on the other 

 parts of the body being loose and unconnected with the 

 parts beneath. 



The use of this layer of the integument, is to corrugate 

 the skin, and elevate the hairs, feathers or spines with which 

 it is furnished. 



5. Cellular web. This forms the innermost layer of the 

 common integuments, and rests immediately on the flesh 

 of the body. It consists of plates crossing one another in 

 different directions, and forming a cellular membrane, va- 

 rying in its thickness, tenacity and contents, according to 

 the species. In frogs it does not exist. The cells of this 

 membrane are filled with various substances, according to 

 the nature of the animal. In general, they contain fat, as 

 in quadrupeds and birds. In some of these, the layer is in- 

 terrupted, as in the ruminating animals, while it is conti- 

 nuous in others, as the boar and the whale. In birds, 

 while a part of this web is destined for the reception of fat, 

 other portions are receptacles for air. In the moon-fish, 

 the contained matter resembles albumen in its chemical 

 characters. 



Where this layer of subcutaneous fat is of considerable 

 thickness, the sensibility of the skin above is greatly dimi- 

 nished. Hence, it is considered as destined to weaken the 

 impressions of external injuries, and to protect against the 

 oflect of the changes of temperature in the surrounding ele- 

 ment. But it is subservient to more important purposes in 

 ihc animal economy. The cells arc the magazines, into 



