286 HAND-BOOK OF PHYSIOLOGY. 



(4.) Saline and saccharine matters, as common salt, or cane sugar, 

 if not in a state of solution beforehand in the saliva or other fluids which 

 may have been swallowed with them, are at once dissolved in the stomach, 

 and if not here absorbed, are soon taken up in the small intestine; the 

 blood-vessels, as in the last case, being chiefly concerned in the absorp- 

 tion. Cane sugar is in part or wholly converted into grape-sugar before 

 its absorption. This is accomplished partially in the stomach, but also 

 by a ferment in the succus entericus. 



(5.) The liquids, including in this term the ordinary drinks, as water, 

 wine, ale, tea, etc., which may have escaped absorption in the stomach, 

 are absorbed probably very soon after their entrance into the intestine; 

 the fluidity of the contents of the latter being preserved more by the con- 

 stant secretion of fluid by the intestinal glands, pancreas, and liver, than 

 by any given portion of fluid, whether swallowed or secreted, remaining 

 long unabsorbed. From this fact, therefore, it may be gathered that 

 there is a kind of circulation constantly proceeding from the intestines 

 into the blood, and from the blood into the intestines again; for as all the 

 fluid a very large amount secreted by the intestinal glands, must come 

 from the blood, the latter would be too much drained, were it not that 

 the same fluid after secretion is again re-absorbed into the current of blood 

 going into the blood charged with nutrient products of digestion com- 

 ing out again by secretion through the glands in a comparatively un- 

 charged condition. 



At the lower end of the small intestine, the chyme, still thin and pul- 

 taceous, is of a light yellow color, and has a distinctly faecal odor. This 

 odor depends upon the formation of indol. In this state it passes through 

 the ileo-caecal opening into the large intestine. 



SUMMARY OF THE DIGESTIVE CHANGES IN THE LARGE INTESTINE. 



The changes which take place in the chyme in the large intestine are 

 probably only the continuation of the same changes that occur in the 

 course ocf the food's passage through the upper part of the intestinal canal. 

 From the absence of villi, however, we may conclude that absorption, 

 especially of fatty matter, is in great part completed in the small intes- 

 tine; while, from the still half-liquid, pultaceous consistence of the chyme 

 when it first enters the cagcum, there can be no doubt that the absorption 

 of liquid is not by any means concluded. The peculiar odor, moreover, 

 which is acquired after a short time by the contents of the large bowel, 

 would seem to indicate a further chemical change in the alimentary mat- 

 ters or in the digestive fluids, or both. The acid reaction, which had dis- 

 appeared in the small bowel, again becomes very manifest in the caecum 

 probably from acid fermentation-processes in some of the materials of 

 the food. 



