PAR VAGUM. 



899 



dticed evidence to shew that these morbid 

 changes do not necessarily follow the division 

 of both vagi in all animals, and that the dog in 

 a few rare cases may either die of inanition 

 from the arrested secretion of the gastric juice 

 and without any morbid alterations in the 

 lungs, or may even survive the operation and 

 recover from its effect. 



Magendie, Wilson Philip,* Mr. Swan,f and 

 Longet,J found that section of one vagus in- 

 duced diseased action in the lung of the same 

 side. The lesions observed by these experi- 

 menters differed very considerably in their 

 character. Dupuytren, on the other hand, 

 could discover no alteration in the lung of the 

 side on which the vagus had been divided in 

 two dogs and a horse, though these animals 

 were allowed to live more than a month. In 

 an experiment made by Magendie before his 

 pupils, the results were completely at variance 

 with his former expressed opinions. The right 

 lung of a dog was found perfectly healthy, 

 though a portion of the vagus of that side was 

 removed six months before. || We have re- 

 moved a portion of one vagus in seventeen 

 animals, and allowed them to live a longer or 

 shorter period, from twenty-four hours to six 

 months, and in none of these could we detect 

 any morbid changes in the lungs which we 

 could attribute to the injury of the nerve. This 

 immunity of the lung from the usual morbid 

 changes, when one nerve only was divided, we 

 attribute to the smaller diminution of the 

 respiratory muscular movements, than when 

 both nerves are divided. 



Functions of the gastric branches. Do 

 the gastric branches of the vagus contain 

 some mot iferous filaments ? Mr. Mayo f and 

 Miiller** failed in exciting muscular contrac- 

 tions in the stomach by irritating the trunks of 

 the vagi, while this experiment succeeded in the 

 hands of Bichat,ft Tiedemann and Gmelin, JJ 

 and Longet. Breschet and Milne Edwards |||| 

 inferred that muscular movementscan be excited 

 in the stomach of a living animal by galvanizing 

 the lower end of the divided vagi in the neck 

 from its effects upon the digestive process. We 

 have carefully and repeatedly performed the ex- 

 periment of irritating the vagi, and are confident 

 that though it occasionally fails, yet it often suc- 

 ceeds.^ These muscular movements in thesto- 

 mach differ considerably from those in the oeso- 

 phagus. They are more slow and are vermicular. 



* Experimental Inquiry, &c. p. 145. 



t Essay on the Connection of the Heart and the 

 Functions of the Nervous System, &c. 



J Opus cit. p. 351. 



j Biblioth. Med., 1807, t. xvii., p. 21., as 

 quoted by Longet. 



|| Le9ons sur les Phenomenes Physiques de la 

 vie, torn, i., p. 203-4. 



^T Anatomical and Physiological Commentaries, 

 No. 2, p. 15. 



** Elements of Physiology. 



tt Anatom. Generale, torn, iii., p. 360. Paris, 

 1812. 



+J Recher. Experim. Physiol. et Chem. sur la 

 Digestion, p. 374. 



$ Opus cit., p. 322. 



lid Archiv. Gen. de Med., tome vii. 



1 1f Opus cit. 



They generally commence at the cardiac orifice 

 and proceed to a greater or less extent towards 

 the pyloric orifice. Longet thinks that he can 

 explain this discrepancy in the results of this 

 experiment, as he found that it succeeded 

 when the stomach was engaged in the process 

 of chymification, and failed when it was empty. 

 Though we are satisfied that the gastric branches 

 of the vagus contain some motor filaments, yet 

 we do not believe with Breschet and Milne 

 Edwards, Brachet, Longet, and others, that the 

 muscular movments of the stomach depend 

 entirely upon the integrity of the vagi. Ma- 

 gendie* observed these muscular movements 

 continue after section of the vagi; and we ascer- 

 tained from experiment that if a dog recovers 

 from the first effects of the operation of cutting 

 the vagi, the stomach can still propel the chyme 

 onwards into the duodenum. Arnold,f from 

 his experiments upon hens and pigeons, con- 

 cludes that the contractions of the stomach are 

 less influenced than those of the oesophagus and 

 crop by division of the vagi. The grains taken 

 into the stomach after this operation were found, 

 however, to be considerably less bruised than 

 in sound animals. 



Effects of lesion of the vagi upon the setisa- 

 tions of hunger and satiety. Though the sensa- 

 tion of hunger is referred to the stomach, yet it 

 is evident from well established facts that this 

 sensation is actually situated in the encephalic 

 portion of the nervous system. This sensation 

 is not dependent, as far as we know, upon any 

 physical condition of the stomach itself, and in 

 all probability arises from certain organic 

 changes in the body, connected with the want 

 of additional supplies of nutritious matters 

 from without. Brachet relates two experiments 

 to show that the sensations of hunger and 

 satiety are arrested by section of the vagi,j but 

 these are liable to certain sources of fallacy 

 against which proper precautions were not 

 taken. Four of seventeen dogs we experimented 

 on, lived beyond the fifth day after the division 

 of the vagi, and exhibited no signs of having lost 

 the sensation of hunger ; on the other hand 

 their actions indicated that they still retained 

 this sensation. Longet has from his experi- 

 ments arrived at conclusions on this point 

 similar to ours. There can be no doubt that 

 the sensation of hunger is almost always sus- 

 pended for a longer or shorter time after the 

 division of the vagi, probably occasioned in 

 some measure by the pain and terror attending 

 the operation, but if the animal live for a few 

 days the sensation of hunger may return. 



Though the facts from which Brachet has 

 arrived at the conclusion that the sensation of 

 satiety is annihilated by the division of the vagi, 

 do not, as we have elsewhere shown,|| warrant 

 this inference, yet it is probable for reasons 

 which will occur to every one in reflecting 



* Compendium of Physiology. Translated by 

 Milligan, 4th edit., p. 261. 



f Bemerkungen u'her den Bau des Hirns und 

 Ruckcnmarks, &c., S. 145. 



| Systeme Nerveux Ganglionaire Expt. 52-3. 



vj Opus cit., torn, ii., p. 3'J9. 



|| Opus cit. 



3 M 2 



