There are, moreover, certain experiments made by Valentin which show that the branches of the sympathetic which are dis tributed to the walls of the blood-vessels, exercise an influence over their contractions. Thus, when stimulus was applied to the tho racic portion of the sympathetic in the horse, he observed that the thoracic aorta and tho racic duct diminished in calibre to a much greater extent than could be attributed to the mere action of the atmospheric air. Iti a newly killed young rabbit, in which the part of the vena cava next the heart, as well as the right auricle %ere pulsating, lie found on applying the wires of the magneto-electric apparatus to the right ventricles, that all con traction in the vessel immediately ceased.
Whatever influence the nervous system exercises over the processes of nutrition, it would seem that the sympathetic cannot be regarded as the only nerve concerned : the cerebro-spinal sy-stem also appears to share therein. In addition to what has been al ready stated, p. 470., there are also other facts which favour such a view. Thus Ma gendie found that, where the spinal cord was divided in the region of the neck, a disor ganisation of the eyeball followed, similar to that which ensues upon division of the fifth nerve. Schiff* has observed that when the crus cerebri or optic thalamus in the rabbit was cut across, the secretions of the intestinal canal become altered; the excrements are slimy and mingled with blood ; the digestion is interfered with, the animal, towards the end of the first week, losing all appetite for food. After death the mucous membrane of the stomach and bronchi was found to be more or less injected with blood, the former also being softened. Similar appearances were also observed in the upper half of the small intestine. That, moreover, the influence ex ercised by the sympathetic over these pro cesses does not differ from that exercise(' by the cerebro-spinal system, is indicated by the circumstance that several glandular (agans, such as the naanitnary and salivary glands, derive their nerves chiefly from cerebro-spinal nerves.
From the experiments of Schiff and others it would appear, however, that the ganglionic system of' nerves is more intimately con nected with these processes than the strictly cerebro-spinal nerves are. Thus, Schiff found,
in regard to the fifth nerve, that when it was divided between the brain and Gasserian gan glion, the destruction of the textures of the eyeball follow more slowly then when it is divided between the ganglion and the eye. In the frog, also, when the lumbar plexus was divided, the animal continued for two or three months without any disturbance being ob served in the nutrition of the limb ; but when several of the hunbar ganglia were retnoved, dropsical effusion into the abdominal cavity, and inflammation of the peritoneum, ending in the death of the animal, ensiled in the course of two weeks.f Axmann t, as quoted by Va lentin, divided at their roots the nerves which supply the posterior extremity in the frog, but in no instance observed that the opera tion ivas followed by any disturbance in the nutritive processes : wounds of' the soft tex tures as well as of the bones healed as rapidly is in the sound leg. When he divided the trunk of the lumbar nerves below the spinal ganglia the skin became gradually pale, its pigment cells diminishing to mere points ; the structures softened ; the liver and kidney no longer secreted ; while dropsical, effusions, containing the elements of the bile and uric acid, at the same time took place. The blood corpuscles also gradually disappeared. The vessels of the spinal cord and of its mem branes became very. much distended with blood. When the lower portion of the sym pathetic cord on either side was removed, the blood-vessels of the hind leg and pelvic organs became highly congested ; the contractility of the muscular tissue in the legs and in the pelvic organs disappeared. Blood was ex travasated into the bladder and rectum, secre tion of urine ceased, and dropsical effusions took place. The circumstance that section of sensory nerves is followed by derangement in the nutritive processes much more quickly than sitnilar lesions of motor nerves is also ex plained by Volkmann as due to the fact of the former containing a comparatively larger number of fine or sympathetic fibres.