144 A Manual of Veterinary Physiology. 



in the ileum the contents are always markedly alkaline. 

 I have only once found them acid in the horse, no matter 

 what diet has been given, or the period of digestion : neutral 

 or faintly alkaline in the anterior part of its course, markedly 

 alkaline in the posterior portion, is doubtless the rule rather 

 than the exception. 



Physical Characters of the Chyme.— The chyme having 

 passed into the bowel, its appearance at once changes, for 

 the acid albumin is precipitated by the alkaline secretion 

 found there. It is now observed that the material consists 

 of clots floating or suspended in a yellowish fluid, extremely 

 slimy in nature, and resembling in appearance, through its 

 precipitated albumin, nasal mucus suspended in fluid. The 

 proportion of mucin must be considerable, judging from 

 the manner in which it pours, and this mucus is probably 

 derived from the stomach. Throughout the small intestines 

 this condition obtains, viz., a yellow, frothy, precipitated, 

 slimy, intestinal fluid ; but we observe in that fluid taken 

 from the latter part of the small intestines that it has a 

 distinctly focal odour, while that from the early intestines 

 has a peculiar mawkish smell. In the ileum the proportion 

 of fluid material is reduced considerably in amount, and 

 we are capable of recognising the nature of the ingesta, 

 which previously was almost impossible. 



As the flow of material into the small intestines is con- 

 trolled by a sphincter, so is the flow out of it. The ileum is 

 a remarkably thick and powerful bowel ; it is always found 

 contracted and containing ingesta, which is dry compared 

 with that found in the anterior portion of the bowel. One 

 of the functions of the ileum is to control the passage of 

 material into the caecum. 



Colin describes the food as circulating between the 

 pylorus and ileum, viz., that it is poured backwards and 

 forwards in order to expose it sufficiently to the absorbent 

 surface. This would necessitate a reversed peristaltic 

 action. He says that were it not tor this the material 

 could not be acted upon and absorbed, as the passage of 

 fluid through the small intestines is so very rapid. It 



