102 . ||| 



depend upon the obstruction of the pylorus*, on the too irritating impres- 

 sion of any substance on the coats of the stomach ; it may be produced 

 by the irritation of some other organ with which the stomach is in sym- 

 pathy, &c. 



Digestion in the stomach is essentially assistefl by nervous influence. 

 Many physiologists, since Brunner, have found that the tying of the eighth 

 pair of nerves (the pneumo-gastric) provoked vomiting and retarded 

 the work of digestionf. As it is impossible to make this experiment 

 without effecting respiration, a function of very different importance, it 

 becomes difficult to know, whether the derangement of digestion did not 

 proceed from the general disturbance brought upon all the functions: 

 however, the brain does appear to be in more immediate sympathy with 

 the stomach, than with any other part of the digestive tube. Disgust 

 from the recollection of loathed food excites vomiting. A more than 

 ordinary exertion of the brain relaxes, disorders, and will even suspend, 

 altogether, the functions of the stomach: an unexpected piece of news, 

 a violent emotion, are attended with a cessation of the strongest sensation 

 of hunger. It would be useless to bring together, in this place, proofs of 

 the intimate connexion subsisting between the brain and the stomach, 

 through the intervention of the pneumogastric nerves, for the connexion 

 is questioned by no onej. 



XXV. Of Digestion in the Duodenum. The food, on quitting the sto- 

 mach, enters the duodenum, and there experiences new changes, as es- 

 sential as those which were produced upon it, by digestion in the sto- 

 mach. It might even be said, that as the essence of digestion and its 

 principal object is the separation of the food into two parts, the one re- 

 crementitious and the other chylous or nutritious, the duodenum, in 

 which that separation is performed, is its principal organ. In fact, how- 

 ever carefully one may examine the greyish chyme which is sent out of 

 the stomach, it will be discovered to be a mere slimy homogeneous pulp ; 

 and in more than a hundred animals which I have opened during the pro- 

 cess of digestion, I never observed the absorbents of the stomach filled 

 with real chyle, like those of the intestines. 



The duodenum may be considered as a second stomach, very distinct 

 from the other small intestines, by its situation exterior to the perito- 

 neum, by its size, and by its readiness of dictation, the size and regula- 

 rity of its curvatures, the great number of valvulse conniventes with 

 which its inner part is furnished, the prodigious quantity of chylous ves- 

 sels which arise from it, and especially by its receiving, within its cavity, 

 the biliary and pancreatic fluids. If the situation of the duodenum and 

 the peculiarities of its structure are attended to, it will be readily observ- 

 ed, that every thing in that intestine, tends to slacken the course of the 



* The best description of the pyloris is given by BLUMEJTBACH from LEVELLING, 

 who designates in an annular fold, " consisting 1 not, like the other i-ugac of the stomach, 

 of merely the mucous, but also of fibres derived from the nervous and musular coats. 

 All these, united, form a conoidal opening' at the termination of the stomach, project- 

 ing- into the duodenum, as the uterus docs into the vaginia, and, in a manner, embraced 

 by it." Copland. 



\ Dr. Haig-hton lias proved, in the most satisfactory manner, that a lig-ature on the 

 eighth pair of nerves, far from inducing- vomiting-, renders the stomach incapable of 

 rejecting its contents, even though excited by the most powerful emetics. See Me- 

 znoirs of the London Medical Societv Trans. Vol. II. P- 512. DeLvs. 



* See APPENDIX, Note L. 



