176 FUNCTIONS OF THE NERVOUS SYSTEM. 



235. The experiments of Dr. Reid do not furnish grounds for a positive 

 determination of the functions of the gastrk portion of the Par Vagum ; but 

 they furnish important correction of the results obtained by others. He has 

 succeeded, as formerly stated ( 198), in producing movements of the stomach, 

 by irritation of the Vagi ; but that these movements may be excited in other 

 ways, is evident from the fact that, in several of his experiments, food was 

 digested and propelled into the duodenum subsequently to the operation. The 

 same fact, which he appears to have fully substantiated, is an incontrovertible 

 proof, that the secretion of gastric juice is not dependent on nervous influence 

 supplied by the Par Vagum, though doubtless in part regulated by it. The 

 first effects of the operation, however, are almost invariably found to be vomit- 

 ing (in those animals capable of it), loathing of food, and arrestment of the 

 digestive process ; and it is not until after four or five days, that the power 

 seems re-established. In the animals which died before that time, no indica- 

 tion of it could be discovered by Dr. R.; in those which survived longer, great 

 emaciation took place ; but when life was sufficiently prolonged, the power of 

 assimilation seemed almost completely restored. This was the case in four 

 out of the seventeen dogs experimented on ; and the evidence of this restora- 

 tion consisted in the recovery of flesh and blood by the animals, the vomiting 

 of half-digested food permanently reddening litmus paper, the disappearance 

 of a considerable quantity of alimentary matter from the intestinal canal, and 

 the existence of chyle in the lacteals. It may serve to account in some degree 

 for the contrary results obtained by other experimenters, to state that seven 

 out of Dr. R.'s seventeen experiments were performed before he obtained any 

 evidence of digestion after the operation ; and that the four which furnished 

 this followed one another almost in succession ; so that it is easy to understand 

 why those, who were satisfied with a small number of experiments, should 

 have been led to deny it altogether. [*] 



236. Another series of experiments was performed by Dr. Reid, for the pur- 

 pose of testing the validity of the results obtained by Sir B. Brodie, relative to 

 the effects of section of the Par Vagum upon the secretions of the stomach, 

 after the introduction of arsenious acid into the system. According to that 

 eminent Surgeon and Physiologist, when the poison was introduced after the 

 Par Vagum had been divided on each side, the quantity of the protective 



[* M.Bernard has instituted fresh experiments to determine this still-debated question, 

 making use of the artificial fistulous openings into the stomach, invented by M. Blondlot. 

 A dog's digestion had been thus watched for'eight days, and had always been well 

 effected. On the ninth day, after a day's fast, M. Bernard sponged out the stomach, 

 which contracted on the contact of the sponge, and at once secreted a large quantity of 

 gastric fluid; he then divided the pneumogastric nerves in the middle of the neck, and 

 immediately the mucous membrane, which had been turgid, became pale, as if exsan- 

 guine, its movements ceased, the secretion of gastric fluid was instantaneously put a stop to, 

 and a quantity of ropy neutral mucus was soon produced in its place. After this, no 

 digestion was duly performed, and milk was no longer coagulated; raw meat remained 

 unchanged, and the food (meat, milk, bread and sugar, which the dog had before tho- 

 roughly digested) remained for a long time neutral, and at last acquired acidity only from 

 its own transformation into lactic acid. In the stomachs of other dogs after the division 

 of the nerves, he traced the transformation of cane-sugar into grape-sugar in three or 

 four hours; and in ten or twelve hours the transformation into lactic acid was complete. 

 In others, when the food was not capable of an acid transformation, it remained neutral 

 to the last. In no case did any part of the food pass through the peculiar changes of 

 chymification. In a last experiment, he gave to each of two dogs, in one of which he 

 had cut the nerves, a dose of emulsine and half an hour after, a dose of amygdaline 

 (substances which are innocent alone, but when mixed produce hydrocyanic acid). The 

 dog, whose nerves were cut, died in a quarter of an hour, the substances being absorbed 

 unaltered and mixing in the blood: in the other, the emulsine was changed by the action 

 of the gastric fluid before the amygdaline was administered, and it survived. Gazette 

 Mid., Juin 1, 1844, from the Report of the Acad. des ScL, seance du 27 Mai, 1844. M. 0.] 



