108 THE WORK OF THE DIGESTIVE GLANDS. 



circulation in other ways than by means of the stomach. The results 

 of experiments on this point speak most decidedly against the hypo- 

 thesis. Many investigators have injected meat broth and solutions of 

 Liebig's Extract per rectum into animals, but have never seen an indi- 

 cation of gland activity. 



Dr. Lobassoff has also investigated this question with great care. 

 He administered to his dogs, per rectum, much larger doses of meat 

 extract than would suffice to induce a secretion if injected into the 

 stomach. By washing out the rectum and investigating the wash- 

 water both physiologically and chemically, he convinced himself that 

 the excitatory material of the extract had disappeared. Hence we are 

 driven by a process of exclusion to the imperative deduction that our 

 miniature stomach, even in the later phases of secretion, is excited 

 through nervous channels that is to say, by reflex stimuli from the 

 larger cavity. We also further conclude that secretion in the large 

 stomach likewise depends on reflex events. But if these exist, it may 

 be taken that, under the conditions of gastric digestion, the reflex must 

 be a diffuse, and not a mere local one ; that is to say, the excitation of 

 a definite area of mucous membrane occasions a secretion not alone at 

 this area but over the whole mucous membrane of the stomach. As a 

 matter of fact, a localised response would have little meaning, since the 

 food itself is in constant motion, and is rapidly moved from the point 

 of stimulation to another. It is, therefore, quite natural that the 

 effects of excitation of the inner surface of the large stomach should be 

 constantly and accurately transmitted to the small one (which, after all, 

 is only a piece of the large), if the nervous connections of the cul-de-sac 

 have been preserve! uninjured. These conclusions receive important 

 confirmation when we compare the activity of a gastric cul-de-sac, isolated 

 according to our method, with one made after the method of Heidenhain, 

 in which the vagus fibres are severed. The dog operated upon by our 

 method, now three and a half years ago, still manifests an exactly similar 

 course of secretion in the two cavities under the same conditions. But the 

 cids-de-sac formed by Heidenhain's method in the course of time have 

 their secretory capabilities very essentially altered. In the beginning, 

 they work very energetically : after a full meal their secretion is copious 

 and lasts for several hours (Heidenhain, Ssanozki). If, however, the 

 animals live long, a gradual decline of the secretion is noticeable, and a 

 month or six weeks after the operation, even after a full meal, it lasts for 

 only three to five hours, growing less and less from hour to hour. Further- 

 more, the dogs thus operated upon do not manifest the characteristic 

 alterations in the work of the glands dependent on differences in the food, 

 which we depicted in the second lecture. In such animals the variations 

 are occasioned by differences in the water contents of the food eaten. 



