13-i OF FOOD, AND THE DIGESTIVE PROCESS. 



separates the two portions of the stomach into a sort of hourglass form ; 

 and Dr. Beaumont states that, when he attempted to introduce a long ther- 

 mometer tube into the pyloric portion of the stomach, the bulb was at first 

 gently resisted, then allowed to pass, and then grasped by the muscular pa- 

 rietes beyond, so as to be drawn in : whence it appears that the contraction 

 has for its object, to resist the passage of solid bodies into the pyloric ex- 

 tremity of the stomach, at this stage of digestion, whilst the matter which 

 has been reduced to the fluid form is pumped away (as it were) by the action 

 of that portion of the viscus. These peculiar motions continue until the 

 stomach is perfectly empty, and not a particle of food or of chyme remains; 

 and when they are nearly brought to a close, the contraction of the pyloric 

 orifice also gives way to an extent sufficient to allow not only the undigested 

 residue of the food, but also large solid bodies that may have been swallowed 

 (such as coins and the like), to pass into the intestinal canal. 



92. With regard to the degree in which these movements of the Stomach, 

 whose share in the Digestive operation is so important, are dependent upon 

 the Spinal cord, and are consequently of a " reflex" nature, it is difficult to 

 speak with certainty, owing to the contradictory results obtained by different 

 experimenters. These contradictions, however, seem partly due to a diver- 

 sity in the nature of the animals experimented on, and partly to a difference 

 in the stage of the digestive process at which the observations were made. 

 The nerve* supplying the Stomach are derived from the Pneumogastrics, and 

 from branches of the solar plexus of the Sympathetic, and it seems to be 

 well established by the researches of Keid, Valentin, and others, 1 that dis- 

 tinct movements commencing at the cardiac orifice, and extending peristal- 

 tically towards the pylorus may be excited, when the stomach is distended 

 with food, by irritating the Pueumogastric. The movements, however, are 

 comparatively feeble when the stomach is empty. When the Pneumogastrics 

 are divided in the neck, the cardiac orifice of the stomach becomes spasmodi- 

 cally contracted 2 a condition which, after lasting for about thirty-six hours, 

 generally passes off. If previously to that period the animal be allowed to 

 eat, the food accumulates in the lower part of the oesophagus, and death re- 

 sults from suffocation. The contraction of the cardiac sphincter appears, 

 therefore, to be induced by other nerves than the Pueumogastric; but there 

 is abundant evidence to show that all the ordinary movements of the stom- 

 ach are governed by the Pneumogastrics (or, perhaps, as Schiff believes, by 

 the fibres of the Spinal Accessory coursing in the Pueumogastrics), since if 

 these be divided, complete paralysis of the muscular walls results, whilst 

 lively movements can still be induced by irritation of the lower or distal cut 

 extremity. Irritation of the splanchnic nerves, or of the sympathetic cord, 

 is not followed by any very obvious movements, the former nerves being in 

 fact essentially vaso-motor, and therefore as when stimulated they thus cause 

 contraction of the bloodvessels, they rather tend to inhibit any movements 

 that may be present than to incite them if they are absent. It is found that 

 after the section of the Pneumogastrics, if small portions of food be introduced 

 into the stomach, these can be still propelled onwards, which we must con- 



1 See Dr. Reid's Physiological, Anatomical, and Pathological Researches, chap, v; 

 Valentin, De Funetionibus Nervorum Cerebralium, etc., chap, xi ; also Longet, Aunt. 

 et PhvMol. <lu Systeme Nerveux, torn, i, p. $'23 ; and Physiologic, vol. i, p. 1^4, 1861 ; 

 and Bischoffin Mullet's Archiv, 1843. Pineus, Exp. de vi JSVrvi Lagi, Wralislaw, 

 1850; Ilarting, Uelier die Ncrvi Vagi, Giessen, 18o8 ; Schin", Physiologic, 1859, p. 

 420; and Schweiz, Monats. 1' Praia. ,Med., I860; Bernard, Med. Times and Gaz., 

 1800, vol. ii, p. 1; Uavitsdi, Miiller's Archiv, 18(il, p 779; Henle, Handh. d. Sys- 

 tem. Anal. di!.s Menschen, Band ii, 1806; 0. Nasse, Beitriigo zur Physiologic d. 

 Darmbewegung, 1800. 



2 Bernard, Med. Times and Gaz., 1860, vol. ii, p. 1. 



