870 INFLUENCE OF NERVES ON NUTRITION. [BOOK n. 



lips and gums. And similar results have been seen in other 

 animals including man. If the operation be conducted in a young 

 animal, which subsequently lives to maturity, the head may be- 

 come bilaterally unsymmetrical, as shewn especially by the skull. 

 Again division of both vagus nerves is very apt to be followed 

 by inflammation of both lungs, by fatty degeneration of the heart, 

 and so by death. 



In several of these instances the effect is a mixed one and 

 the problem complicated. Thus, in the case of division of the 

 fifth nerve, seeing how delicate a structure the eye is, and how 

 carefully it is protected by the mechanisms of the eyelids and tears, 

 it seems reasonable to suppose that the inflammation in question 

 might simply be the result of the irritation caused by dust and 

 contact with foreign bodies, to which the eye, no longer guided and 

 protected by sensations, these being destroyed by the section of the 

 nerve, became subject. In the same way the ulcers on the lips and 

 gums might be explained as injuries inflicted by the teeth on 

 those structures in their insensitive condition. And some observers 

 maintain that the inflammation of the eye may be greatly lessened 

 or altogether prevented if the organ be carefully covered up and in 

 all possible ways protected from the irritating influences of foreign 

 bodies. Other observers however have failed to prevent the in- 

 flammation in spite of every care. So also the inflammation of 

 the lungs following upon division of both vagus nerves seems to be 

 due not to any direct nutritive action of the pulmonary branches 

 of the vagus on the pulmonary tissue, but to food accumulating in 

 the pharynx owing to the paralysis of the oesophagus and larynx, 

 and then passing into the air passages and so setting up inflamma- 

 tion. The operation however may be so carried out that the 

 glottis is not paralysed, the food does not enter the lungs, and no 

 inflammation of those organs takes place. Nevertheless the animals 

 waste and die, and that so rapidly that death cannot be attributed 

 to mere inanition due to paralysis of the oesophagus. Gastric 

 disorders are observed and the contents of the stomach become 

 crowded with bacteria ; but the exact cause of death is uncertain, 

 and the phenomena do not afford clear evidence of a special nutritive 

 nervous action. The phenomena of the paralytic secretion of saliva 

 are also of a complicated nature. 



But even without insisting on such instances as the above, 

 various other phenomena of disease seem to indicate such an 

 influence of the nervous system on nutrition as we are discussing. 

 As examples we might mention the rapid and peculiar degenera- 

 tion of and loss of contractility in the skeletal muscles in certain 

 affections of the spinal cord, the changes in the muscles being 

 more rapid and profound than in the nerves ; the phenomena 

 of bed-sores, especially the so-called acute bed-sores .of cerebral 

 apoplexy ; some at least of the cases of vesical affections attendant 

 on spinal or cerebral diseases or injuries ; the more rapid atrophy 



