226 BIOLOGICAL PHYSICS 



and the glosso-pharyngeal muco-colloid excretion are 

 intimately mixed with the pristine alimentary materials, on 

 some of which they must immediately act, while, on others, 

 they may subsequently exert a digestive influence. The 

 oesophageal digestive influence, must consist of admixture 

 with the local mucous discharge, and what mechanico- 

 chemical change is effected in transit to the stomach. The 

 gastric digestion is a long, and complex process, combin- 

 ing the effects of mechanical, chemical, and physiological, 

 influences, and culminating in removal, by absorptive 

 agency, of a considerable portion of the alimentary 

 material, while the duodeno-jejuno-ileal digestion, from 

 the extent of surface passed over, and the many fluids 

 mixed with the chyle during its prolonged transit, must be 

 of scarcely less importance than that of the stomach, 

 although the articles of food digested differ in chemical, 

 and other characteristics, from those dealt with in the 

 stomach. In both these digestions the dynamic agencies 

 at work comprise mechanical, chemical and physiological, 

 acting singly and in combination, in ordinary, as well as, 

 specific manner, and having the effect of securing the 

 absorption ot a large proportion of the principal elements 

 of the food, before their passage through the ileo-caecal 

 valve. The caeco-colonal digestion differs very much from 

 the preceding digestions, inasmuch as the alvine contents 

 now become stercoraceous, and can yield for nutritive 

 purposes a lesser quantity, and a somewhat peculiar quality, 

 of digested material, the digestive agencies here, are the 

 same as in the preceding, plus, it may be, the disinte- 

 grative, and specific, influence, of bacterial organisms, or 

 living dynamics, in the form, for instance, of the anaerobic 

 bacillus coli. Following the casco-colonal, is the final stage, 

 of digestion, the rectal, which is separated from the caeco- 

 colonal by the mechanical obstruction, or pseudo-valve, 

 effected by the sigmoid flexure, and which may be regarded, 

 as the inner sphincter, or a safeguard for the sphincter ani. 

 In fact, the sigmoid flexure may be regarded as possessing 

 the function of faecal meter, or fascimeter, if we may use the 

 term, allowing to pass only what is meant for prospective 

 evacuation, and retaining behind what is yet fit to afford 

 further nutriment. Consequently, we may regard the 



