314 



STOMACH AND INTESTINE. 



rent, as that curved line which unites the car- 

 diac and pyloric apertures (a, fig. 245.). 



Fig. 245. 



Diagram to show the general direction of movement 

 impressed on the semifluid food in the digesting 

 stomach. 



a, real axis of the stomach, uniting its cardiac 

 and pyloric apertures ; b, situation of the abnormal 

 opening in St. Martin's case. (The arrows corre- 

 spond to the peripherial current of advance, which is 

 effected by peristalsis ; and the central current of 

 return, which is reflected from the preceding at 

 the pylorus.) 



(2.) The observations of Dr. Beaumont are 

 as follows*: "The bolus, as it enters the 

 cardia, turns to the left, passes the aperture, 

 descends into the splenic extremity, and fol- 

 lows the great curvature towards the pyloric 

 end. It then returns in the course of the 

 smaller curvature, makes its appearance again 

 at the aperture in its descent into the great 

 curvature, to perform similar revolutions. 

 These revolutions are completed in from one 

 to three minutes; the bulb of the thermometer 

 invariably indicates the same movements." 

 He is careful to add, that there is an admix- 

 ture of the ingesta, which implies that the 

 movement is not simply a revolution ; for that, 

 if this were the case, " the central portions 

 would retain their situation, until the outer or 

 chymified part had passed into the duode- 

 num.'^ 



Now in order to render the movement 

 thus observed perfectly compatible with 

 that above deduced, we have but to recollect 

 the situation of the aperture from which the 

 inspection of St. Martin's stomach was made. 

 This was at the left extremity of the organ 

 (, jig. 245.). Whence it is obvious, that 

 any backward movement along the real 

 axis (a), connecting the two orifices of the 

 stomach, would be so near to the superior 

 curved border, and so far from the point of 

 view, that Dr. Beaumont could scarcely have 

 avoided imputing to it the course which he has 

 done. While, since every part of the stomach 

 would be occupied by one or other of the two 

 currents, the mutual interference of these at 



* Op. cit. p. 101. 



t This admixture he ascribes to a triturating or 

 agitating motion, which is partly gastric, partly re- 

 spiratory. But the existence of the circulating 

 movement described sufficiently proves that this 

 mixture was inherent to the process, and not (as 

 his supposition would imply) a result of its disturb - 



their borders must gradually cause an uniform 

 diffusion of the various alimentary matters 

 moving with them. And finally, the reflec- 

 tion of one current into the other at the 

 pylorus, insures an equal contact of all the 

 semifluid food with the surface of the mucous 

 membrane; since those portions of the in- 

 gesta which occupy the axis of the stomach 

 during one moment, are destined to move 

 along its periphery during the next. 



3. In the later stage of digestion, the move- 

 ment seen in the Dog's stomach soon after 

 death differs from the preceding. 



The cardiac extremity appears even less 

 active than before ; and the longitudinal 

 shortening of the organ is also less marked. 

 The chief visible commencement of contrac- 

 tion is at the same place where it was for- 

 merly increased, and where it now forms a 

 deep constriction or hour-glass contraction. 

 After this constriction has continued a short 

 time, it sends onwards towards the pylorus a 

 rapid peristalsis, which appears nearly to ob- 

 literate the tube in its course, and ends by 

 engaging the muscular ring of this valve. A 

 slight relaxation closely follows this peristal- 

 sis ; and is succeeded by a complete dilata- 

 tion of the pyloric sac. Lastly, the hour- 

 glass contraction itself sometimes disappears ; 

 and an interval of about two minutes precedes 

 the repetition of the whole process. Often, 

 however, the constriction remains until the 

 peristalsis recommences. 



Dr. Beaumont's observations * again seem 

 to supply the counterpart to this description. 

 He states that, when chymification has ad- 

 vanced, the motion is quicker. And on attempt- 

 ing to pass a thermometer tube towards the 

 pylorus, it is stopped by a stricture f, which is 

 situated about three or four inches from this 

 aperture. A forcible contraction is first per- 

 ceived ; but in a short time, there is a gentle 

 relaxation, when the bulb passes without dif- 

 ficulty, and is then drawn forcibly towards 

 the pyloric end for three or four inches. It 

 is then released, and forced back with a spiral 

 motion for the same distance, when it seems 

 to be again obstructed by the stricture. But 

 if pulled up through this, it moves freely in the 

 cardiac portion, mostly inclining towards the 

 splenic extremity. The repetition of the con- 

 traction is preceded by an interval of about 

 three minutes, during which the food revolves 

 as in the previous stage. 



It is scarcely necessary to point out, that 

 when the almost obliterated pyloric tube is 

 filled by the tightly grasped thermometer bulb, 

 no axial current can possibly be produced by 

 the peristalsis. The pylorus having con- 

 tracted, and its pouch relaxed, the contrac- 

 tility of the whole organ would determine a 

 rush of fluid around the bulb; and this would 

 be reflected from the valve into the axis of the 



* Op. cit. pp. 102. 104. 



f The similar narrowing seen in the digesting 

 stomach of animals has been called the " transverse 

 band" ; a term which is objectionable, inasmuch as it 

 implies the presence of a special structure that does 

 not reallv exist. 



