ON EMBRYONIC DIFFERENTIATION 269 



judging from the past, it seems likely to afford a perennial 

 theme for discussion, by physiologist and clinician alike, 

 until medical science is with sufficient reason, or, at any 

 rate, entitled, to be called exact. The musculature of the 

 stomach is adapted to the performance of, circular, forward 

 and backward, movements, of its contents, in accordance 

 with the necessities, arising during the functional activity 

 of the organ, or thrust on it, from failure of other parts of 

 the intestinal tube to meet their obligations, in the joint 

 work of intestinal circulation, by normal peristalsis. Anti- 

 peristalsis is a functional endowment of the gastric muscu- 

 lature, whereby the vis medicatrix nature, is enabled to 

 effect, the reversal of a possible pathogenic functional 

 current, and to relieve the physiological factors of the 

 necessity of dealing with dangerous elements, alimentary, 

 and others. The gastric musculature is here mainly under 

 the control of sympathetic innervation, and hence is 

 inexorable in its demands on its systemic partner. 



The smaller bowel (see Fig. 1 1 3), consisting of duodenum, 

 jejunum and ileum, is small in lumen, but much longer 

 than any division of the alimentary canal, and has added 

 to its contents a larger quantity of intra- and extra-mural 

 material, than any other division receives, the liver, and 

 pancreas, besides the local mural glandulature, contributing 

 their entire secretions. The bile and pancreatic juice 

 being added, immediately after the duodenum leaves the 

 pyloric orifice of the stomach, and the glandular secretion 

 of the entire extent of the canal of the smaller bowel, 

 added, as the chyme is circulated onwards, chemical and 

 physical changes are constantly occurring, during the con- 

 tinuance of that circulation, by which it is rendered absorb- 

 able by its lining mucosa (see Fig. 113). The stomach 

 having already removed, by osmosis, the more liquid 

 portion of its contents, and prepared the substance of the 

 chyme for digestive treatment, by the smaller bowel, the 

 villi of whose lining membrane are able to absorb, and 

 pass into the capillary terminations of the lacteal vessels, 

 and, necessarily, to some extent, into the blood capillary 

 vessels distributed within it, the materials, which have 

 yielded to the digestive influences here brought to bear 

 on them, with the result, that, only an unyielding 



