276 DIGESTION 



6. THE GLANDS OF THE INTESTINE 



A. GLANDS OF THE SMALL INTESTINE 



In fasting animals scarcely any secretion of intestinal juice takes place. 

 But if the intestinal mucosa be stimulated directly, either by mechanical,, 

 electrical or chemical means, or if food be ingested, it makes its appearance. 

 Whether an isolated loop of the intestine into which no food can pass begins 

 to secrete without direct stimulation, must, in view of recent discoveries, be 

 regarded as very doubtful. 



If the nerve fibers running in the mesentery beside the blood vessels to an 

 intestinal loop be cut, either immediately or after some time, an extremely abun- 

 dant secretion appears in the loop, whereas the adjacent parts of the intestine 

 outside of the tract deprived of its nerves show nothing of the kind. This secre- 

 tion, which may reach the enormous value of one-eleventh of the body weight, 

 continues for some hours, becomes somewhat scanty after four or five hours, but 

 does not cease within twenty-four hours. At first the secretion is quite clear, 

 containing no solid flakes, or at least only a few ; but as time goes on the quantity 

 increases so that finally a veritable " pap " is produced. At times the secretion 

 is milky, like a thin gruel, and contains an abundance of intestinal epithelia 

 (Moreau). Somewhat similar phenomena, more or less degenerative in character, 

 make their appearance after extirpation of the coeliac plexus. 



It is not easy to explain this secretion. We might regard it as primarily a 

 transudation of fluid caused by the vasodilatatiori, and not as a true process 

 of secretion at all if our knowledge of transudation in general did not speak 

 decisively against such an explanation. If it were an actual secretion of the 

 glands of Lieberkiihn a view which is confirmed by the properties of the fluid 

 it were easy to assume that the nerves whose section produced the hypersecretion 

 exert a tonic influence which inhibits the glands. When the glands escape from 

 this inhibitory influence they fall into the condition described. This hypothesis 

 assumes that in the intestine itself conditions are present which would set the 

 glands in excessive action, if they were not restrained by the nerves. But we 

 know nothing more about it. Meantime let it be remembered as was remarked 

 concerning the other digestive glands the paralytic secretion of the salivary 

 glands, etc. that certain phenomena have been observed which point to such an 

 inhibitory influence. 



Other than this we have no knowledge of an ultimate influence of the ner- 

 vous system upon the secretion of the intestinal juice. Vagus stimulation thus 

 far has given only negative results. 



So far as the few scattered observations on this subject go, the secretion 

 of the lower part of the small intestine seems to be more abundant than that 

 of the upper. It is stated also that the quantity of slimy flakes in the upper 

 parts is greater. These flakes consist essentially of swollen cellular elements 

 (epithelial cells and leucocytes) and of desquamated cells undergoing fatty 

 degeneration. 



If the two ends of an isolated loop of the intestine be sewed together and 

 the intestinal ring thus formed be lowered into the abdominal cavity, one finds, 

 when the animal is killed some months later, that the intestinal ring is filled 

 full of a semisolid mass (Hermann). This mass, like the above-mentioned flakes 

 in the intestinal juice, consists of dead cellular elements. It appears therefore 



