SOLID PARTS OF ANIMALS. 



which communicate with each other. It fills up all the inter- 

 stices and penetrates into the muscles. 



The cellular tissue consists of a matter which, when boiled in 

 water, becomes soft and mucilaginous, and is at last converted 

 into gelatin. 



The cells of the cellular tissue are always moistened by a li- 

 quid secreted for the purpose ; and which in a state of health is 

 absorbed as fast as it accumulates. But in the disease called 

 anasarca or general dropsy this liquid is secreted probably in 

 greater abundance than in a state of health, while the absorbents 

 either cease to act, or act imperfectly. Hence the liquid accu- 

 mulates, fills all the cells, and constitutes the disease called dropsy. 

 In such cases it may be drawn off in considerable quantities. It 

 has been repeatedly subjected to a chemical examination. The 

 result of these analyses will be given in a succeeding chapter of 

 this work, while treating of lymph, to which liquid it obviously 

 belongs. 



In some parts of the body the cells of the cellular tissue are 

 filled with fat. This is the case immediately under the skin, 

 constituting what is called the adipose tissue. Many anatomists, 

 however, consider the fat as enclosed in separate and shut vesi- 

 cles, which have no communication with each other. This opinion 

 is founded on the well known fact, that the fat of the spermaceti 

 whale is fluid, yet it does not collect in the lowermost cells of the 

 cellular tissue, as it would do if the cells or vesicles containing 

 it had a communication with each other like the cells of the cel- 

 lular tissue. Raspail even affirms that he can demonstrate the 

 vesicles in which the fat is contained. Obesity is considered by 

 some physiologists as a disease analogous to anasarca, with this 

 difference, that the cellular tissue is filled with fat instead of lymph. 



CHAPTER XIII. 



OF THE SKIN. 



THE skin is that strong thick covering which envelopes the 

 whole external surface of animals. It is composed of three parts, 

 distinguished by different names, namely, 1. The cutis or true 

 skin, which is innermost and thickest. 2. The rete mucosum lies 



