446 ELEMENTARY ANATOMY. [LESS. 



10. The INTESTINES of man have been described in the 

 Sixth Lesson of " Elementary Physiology," 21 23. It may 

 be here mentioned that the long convoluted tube immediately 

 proceeding from the pyloric end of the stomach is called the 

 small intestine. This terminates by a definite opening (de- 

 fended by a valve) into a much wider and sacculated tube, 

 called the large intestine, or colon (Fig. 374, ac, tc, and dc). 

 Near the point of junction, the end of the colon projects 

 blindly in what is called the c&cuin, which latter has at- 

 tached to it, near its end, a very narrow hollow process, 

 called the vermiform appendix: (Fig. 374, a). The colon 

 ascends in the abdominal cavity, passes transversely, and 

 then descends to terminate in the rectum. In its transverse 

 coarse the colon passes in close proximity to the first part 

 of the small intestine, called the duodenum. 



The intestines, like the stomach, are formed of muscular 

 fibres with a mucous lining ; and this lining is, in the small 

 intestine, drawn out into very numerous folds (called valvulce 

 conniventes}, placed transversely to the course of the bowel 

 and in close proximity, thus vastly increasing the amount of 

 surface in contact with the food. No such folds exist inside 

 the large intestine. 



11. The study of Vertebrates generally shows us that the 

 alimentary canal may be much more prolonged relatively, 

 and may be more complex than it is in man, as also that it 

 may be relatively much shorter and very much simpler than 

 in him. 



In man the intestines are six or seven times the length of 

 the body, but in his own class they may be as little as three 

 times that length, or even less as in Bats and Shrews ; 

 while they may be as much as twenty-seven times as in the 

 Sheep. 



Passing beyond man's class, we find that the intestines 

 may but little exceed the length of the. body, as in many 

 Lizards (Fig. 384) and Serpents, and may even fall short of 

 it, as in some Fishes. 



In that his intestine is divisible into "large" and "small," 

 man agrees with the great majority of members of his sub- 

 kingdom. Nevertheless, all distinctions between these parts 

 may be wanting, so that the whole intestine forms one 

 simple canal, as e.g. in the Carp, and still more strikingly in 

 the Lamprey. Even in man's own class there may be no 

 distinction in size between the large and small intestines, as 

 in the Shrews and there is hardly any in the Porpoise. 



