Though tbe 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 vve have elsewhere shown,11 warrant this inference, yet it is probable for reasons vvbich will occur to every one in reflecting upon the matter that this sensation is inore de pendent upon the physical condition of the storuach than that of hunger. At the same time we must confess that we have ourselves obtained no very satisfactory. evidence from experiment, that this sensation is annihilated by division of the vagi.
Effects of lesion of the vagi upon the flinction of digestion. — That section or liga ture of the vagi is generally followed by vomiting,—in those animals susceptible of it,— by loathing of food and arrestment of the di gestive process, has been incontrovertibly proved by numerous experimenters. That perfect di gestion may occasionally take place after division of the vagi in the neck even when the cut ends are kept considerably apart, is now, we are fully convinced, sufficiei itly established. Leuret and Lassaigne have detailed an experi ment where the process of digestion went on in a horse after division of the vagi with loss of substance.* In one of Amemann's experiments on dogs, the digestive process must have been re-established, as the animal was killed on the 165th day after the operation of dividing both vagi.t In an experiment made by Sedillot on a dog the digestion must at least have been par tially restored, as the animal lived two months and a half.! Sedillot also mentions that Begin kept a dog alive for a month after thedivision of both vagi. M. Chaumet further states that no obvious change was observed in the digestion in this dog ;§ and he also mentions that in some similar experiments made by himself a dog lived fourteen days and digested. In four out of seventeen dogs experimented on, we obtained sufficient evidence of the restoration of the digestive process. In these animals we had not only removed a portion of the vagi, but also of the recurrent nerves. Many experi menters, among whom we may enumerate lialler,11 Brunn,5 De Blainville,** Dumasitt Dupuy,n Legallois,§§ BIacdonald,1111 son Philip,11-5 and Dr.11astings,*** have never obtained evidence of the continuance of the digestion after lesion of the vagi, but such negative experiments cannot be considered as neutralizing the results of the positive experiments we have mentioned above: they only show what every physiologist wbo has experimented much on this subject naust be obliged to confess, that the digestive process is generally arrested after section of the vagi during the short time the animal usually lives after these nerves have been tied or divided, but they can never overthrow the results derived front positive experiments, provided that these have been accumtely performed and are free from all sources of fallacy.
Effects of lesion of the vagi upon the secretion of gastric juice.—We have already detailed facts sufficient to prove that the re moval of a portion of both vagi does not always arrest the digestion of food, and consequently does not necessarily prevent the secretion of the gastric juice. Mayer found the chyme acid in mbbits after section of the vagi. Dieckhof and state that in all their experiments performed upon geese the fluid secreted from the surface of the stomach after section of the vagi was always acid, but was less in quantity than in the sound animal.* Breschet, Milne Edwards, and Vavasseur,t Dr. llolland,r and Brachet,§ maintain that in their experiments the gastric juice was secreted, since the food in the stomach was more or less altered. In two ex periments we ascertained that the half digested food vomited, though taken into the stomach some days after division of the vagi, perma nently reddened litmus-paper ; and we consider the presence of chyle in the lacteals and thoracic duct as observed in the experiment of Leuret and Lassaigne, and in three of our own experi ments, as furnishing decisive evidence of the secretion of g,astric juice. In one of our expe riments the animal was rapidly recovering flesh and strength when he was killed three sveeks after division of the vagi and recurrents with loss of substance. Arnold, in his experiments upon hens and pigeons, ascertained that the fluid secreted from the stomach was acid, that it was not perceptibly diminished in quantity, and that it was capable of converting the food into chyme.II• Longet, in his experiments upon quadrupeds, found that the fluid secreted from the stomach coagulated milk and reddened turnsol paper. lie further states, that the quan tity of gastric juice secreted appeared to him to be greater than in the sound anima1.5 In a great number of experiments, more especially if the animal survive the operation a short time only, the secretion of gastric juice is tempo rarily suspended, and this e,nables us to explain the frequent occurrence of negative results in such researches.