Budge observed that movements were ex cited in the ccecum of the rabbit when the trunk of the vagus-nerve in the neck was stimulated by means of the electro-nia,gnetic rotation apparatus.
As in the case of the heart, so also in regard to the intestinal canal, stimuli applied to the central nervous niasses have been ob served to exercise a greater or less influence in exciting contractions in the intestine. In animals newly killed, Valentin has fre quently observed movements produced in the intestines by division of the anterior and pos terior roots of the spinal nerves. In such experiments, however, it is difficult to ascer tain whether the contraction be due to the stimulus applied to the nerves, or whether it may not be owing to the stimulus of the air acting directly on the intestines them selves. The application of galvanic stimulus leads to more decisive results. When, ac cording to Valentin*, the wires of the mag neto-electric apparatus are applied to the corpora quadrigemina or medulla oblongata, lively contractions are excited in the stomach and intestine. Contractions were also pro duced in the small intestine, great intestine, and rectum, by application of the same stimulus to the spinal cord. In Cyprinus linen, Weber has shown that very powerful contractions may be excited in the stomach by application of the wires of the electro magnetic rotation apparatus to the posterior part of the cerebellum or to the medulla oblongata. The same stimulus applied to the spinal cord in the animal above mentioned, as also in dogs, he observed to be followed by movements in the intestinal canal.
From the experiments of Valentin it ap pears that the movements which are excited in the intestinal canal by stimulus applied to the central masses of the nervous system, are not produced through the medium of the pneumogastric alone. In a rabbit which had been bled to death, and in m hich the ab dominal muscles were removed without injuring the peritoneum, he found, when the wires of the magneto-electric apparatus were inserted into the cerebellum, that very lively movements ensued in the small intestine, al though the two vagi nerves had been pre viously divided in the neck. Budge, how ever, finds that it is only when the two vagi nerves have been left that movements can be excited in the ccecum of the rabbit by appli cation of the galvanic stimulus to the medulla oblong,ata.
The constipation and tympanitis which frequently' attend diseases of the spinal cord, in like manner indicate that the central masses of the nervous system exercise a cer tain influence over the movements of the intestinal canal.
These movements, however, like those of the heart, still continue after the brain and spinal cord have been destroyed. Bidder, as cited by Volkmann, fed several frogs with worms and immediately destroyed the spinal cord : on opening the animal twenty-four hours afterwards, the stomach was found distended with tough slimy matters : if, on the other hand, forty-eight hours were al lowed to elapse before the stomach was examined, it was found almost empty, part of the contents having been probably ab sorbed, while part had passed downwards into the intestinal canal. The continuance of the movements of the intestinal canal after the brain and spinal cord have been removed, would seem to indicate that these are not the immediate centres on which their contractions depend. The contractions which take place may be explained as due to the inherent irritability of the muscular fibres, while their type may be said to be owing to a peculiar arrangement of these, by which the contraction of one bundle acts as a stimulus to the neighbouring bundles, exciting these to contraction also, and in this way giving rise to the vermicular movements of the gut. It seems probable, however, that they are re gulated by the ganglia of the sympathetic, especially since it has been observed by Henle*, that in pieces of the intestine which have been cutaway close to the line of attach ment of the mesentery, the contractions pro• duced by application of local stimuli extend but a little way on either side of the point irritated, and are comparatively feeble. When a part of the mesentery is removed along with the portion of the intestine, they are more powerful and more extended, and are most so when the intestine and mesentery are left in their normal relations.