INTERNAL ORGANS. 25 



cently killed, and in some it continues a con- 

 siderable time after death. The intestine, 

 however, is not entirely composed of muscular 

 fibres; its internal surface is lined with a fine 

 nervous and muscular membrane, which is en- 

 dued with exquisite sensibility, and has the 

 power of forming on its surface a mucous sub- 

 stance, which serves to protect it from the 

 action of acrimonious bodies. Beside the 

 muscular and nervous coat, there is another 

 which enters into the composition of the in- 

 testine : this is a thin membrane trailed peri- 

 tonaeum. The peritonaeum not only forms 

 the third and external coat, it likewise enve- 

 lops all the organs contained in the abdomen, 

 fomiino: their external coat, and is closelv con- 

 nected with them, and is then so reflected as to 

 form a kind of sac, in v»'hich they are all inclosed. 

 Thus are the intestines composed of three 

 coats, which are closely in contact with each 

 other; the peritonaeal, the muscular, and the 

 nervous coat. 



We have yet to describe the course of the 

 lactealsy or those vessels which take up the 

 chjde or nutritious parts of the food. We 

 have before observed that they are spread 

 upon the mesentery, whence they pass ow 



TOL. I. c 



