354 HUMAN PHYSIOLOGY 



the bacillus coli cominunis. The amount of solid faeces 

 depends on the amount of food a fairly average amount 

 per diem is 150 grms. of dried solids. On a vegetable diet, 

 from the presence of undigested cellulose, the amount is 

 very much greater. The solids of the faeces of a feeding 

 animal consist of the same constituents as the faeces in a 

 fasting animal, with the addition of all the undigested con- 

 stituents of the food elastic and white fibrous tissue, remains 

 of muscle fibres, often fat and the earthy soaps of the fatty 

 acids ; and, when a vegetable diet is taken, the cellulose of 

 the vegetable cells, and frequently starch. The cellulose, by 

 stimulating the intestine, is a valuable natural purgative. 



The odour is due to the presence of aromatic bodies such 

 as indol and skatol. 



Meconium is the name given to the first fyeces passed by 

 the child after birth. They are greenish-black in colour, 

 and consist of inspissated bile and shed epithelium from 

 the intestine. 



Movements of the Intestine. 



These are of two kinds myogenic and peristaltic. The 

 myogenic movements are slight rhythmic contractions which 

 pass rapidly along the intestine, and are insufficient to 

 drive on the contents, but are probably of use in churning 

 and mixing them. By feeding with food mixed with bismuth, 

 and employing X rays, Cannon finds that the contents of the 

 small intestine get broken up into small segments. This is 

 possibly due to these myogenic movements (Fig. 149, p. 339). 

 They occur when all the nerves have been divided, and when 

 the ganglia in the intestinal walls have been poisoned with 

 nicotine, and they are therefore due to the muscle fibres 

 alone. 



The peristaltic movements are much more complex and 

 powerful. They consist of a constriction of the muscles, 

 which seems to be excited by the passage of the food, and 

 may be caused by inserting a bolus of cotton-wool covered 

 with vaseline. Starting at the upper end of the intestine, 

 they pass slowly downwards. In front of this contraction 

 the muscular fibres are relaxed, and thus the contracting 



