100 THE BODY AT WORK 



duodenum makes three sharp curves. First it inclines up- 

 wards and to the right, then vertically downwards, then hori- 

 zontally to the left, and finally forwards. The ducts of the liver 

 and pancreas open by a common orifice into the descending 

 portion. Its horizontal portion is bound firmly to the ver- 

 tebral column. After this the whole of the small intestine is 

 supported by the mesentery, a double fold of peritoneum which 

 allows it to hang freely in the abdominal cavity. The mesen- 

 tery is attached to the back of the body-wall. Commencing 

 on the left side of the second lumbar vertebra, its line of attach- 

 ment inclines obliquely downwards and to the right, across 

 the vertebral column, for about 6 inches. Measured from 

 its attached edge to the edge which bears the intestine, 

 it has a width of about 8 inches. Its free border has, as already 

 said, a length of 22 feet. Its measurements being as just stated, 

 it is clear that it must be folded backwards and forwards upon 

 itself, like a goffered frill. In the right groin the small intestine 

 joins the large intestine, or colon. It does not, as might have 

 been expected, simply dilate into the large intestine, but 

 enters it on its mesial side, its orifice being guarded by the ileo- 

 colic valve. In other words, the large intestine projects down- 

 wards beyond this orifice, as the caecum coli. In many animals 

 the caecum is of great length and capacity. In the human 

 embryo it begins to assume a similar form ; but a very small 

 portion only (the so-called " caecum " of human anatomy) 

 dilates to the calibre of the colon. The real caecum retains 

 throughout life its embryonic calibre. It has a length of about 

 3 1 inches, and a diameter of not more than J inch. This is 

 the " vermiform appendix," of ill fame, which must be looked 

 upon as one of Nature's misfits. Its great liability to become 

 inflamed is commonly explained as due to the tendency of such 

 articles of food as pips, the fibre of ginger, flakes from the 

 inside of enamelled saucepans, etc., to become lodged in its 

 cavity. But whether this explanation be correct or no and 

 there are reasons for thinking it somewhat fanciful it is much 

 to be wished that the process of evolution would hasten the dis- 

 appearance of this functionless vestige of a caecum. As there 

 is no tendency towards the inheritance of characters due to 

 mutilation, and since the surgeon's knife now prevents this 

 death-trap from claiming its toll of possible parents, we must 



