21* Small lute/lines. [Book IX. 



differs from that of the ftomach in one refpect, that 

 the longitudinal fibres are here lefs numerous, and the 

 circular fibres much more fo. The fame fibre, how- 

 ever, does not wholly furround the inteftine, as the circle 

 is made of feveral imperfe<5t arches. The cellular 

 coat is exactly the fame as that of the ftomach. It 

 affords ftrength to the inteftines, and conducts nerves 

 and blood-vefiels to and from the villous coat. The 

 villous coat of the fmall inteftines is exceedingly exten- 

 five, and forms, together with the cellular fubftance,, 

 which connects it to the cellular coat, a vaft number of 

 red femilunar folds or wrinkles, which ferve to increafe 

 remarkably the internal furface of the inteftines, and 

 of courfe to expofe the chyle more fully to the mouths 

 of the lacteals. 



The fmall inteftines aflift in the preparation of the 

 chyle, and propel their contents towards the great in- 

 teftines. 



With refpect to the fmall inteftines in particular, 

 feveral circumftances are to be noticed. The duode- 

 num, fo named from its being about twelve inches irt 

 length, differs from the others in not being entirely 

 furrounded by the peritoneal coat ; its mufcular coat, 

 however, is ftronger than that of the other fmall intef- 

 tines, and its colour is more florid. The duodenum, 

 beginning from the ftomach, firft runs towards the right 

 fide downwards, and rather backwards; then it bends 

 towards the right kidney, to which it is flightly con- 

 nected, arid thence paffes before the renal artery and 

 vein, afcending gradually from right to left, till it gets 

 before the aorta and laft vertebra of the back. It con- 

 tinues its courfe obliquely forwards by a gentle turn, 

 and then terminates in the jejunum. Through this 

 whole courfe the duodenum is firmly bound down and 

 concealed by the folds of the peritoneum. The duode- 

 num 



