185 



These Haller regarded as alternate contractions in two directions, 

 now forwards, novv^ backwards, forcing the contained food in corre- 

 spondingly reversed directions, and rested this conclusion on expe- 

 riment and argument ; but the author believes the experiment to be 

 solitary, and not parallel with the fact sought to be established, and 

 the argument to be inconclusive. 



Beaumont's views are cited as analogous to Haller's, but are con- 

 sidered as having been by no means clearly stated. 



The author indicates an argument from analogy, but chiefly bases 

 his conclusion on the observations of Owen and others on Fishes, and 

 his own observations in animals immediately after death : — in the 

 empty or non-digesting stomach ; and in the stomach which contains 

 food ; first, in the early stage of digestion ; and, secondly, at a later 

 period. 



From a contrast of these three states it is found, that in the first 

 there is no movement ; in the second and third a considerable one ; 

 that in the latter, the opening of the pylorus, and the preponderance 

 of the contractions of the pyloric half of the viscus, constitute its 

 chief distinction from the second. The two latter movements are 

 both peristaltic, or in one direction only — being never reversed, so far 

 as the author has seen. 



The movement impressed on the food is next considered. Ac- 

 cording to the observations of Beaumont and others, the food passes 

 in two directions or streams, forwards and backwards. These ob- 

 servations the author has been unable to repeat, but regards them 

 as established. 



Assuming the truth of these observations, and contrasting them 

 with the muscular actions previously stated, it appears that the latter 

 are uniformly in one direction, the former in iivo,—diia. apparent in- 

 congruity, which the author next seeks to explain. 



By experiment he attempts to imitate the natural conditions, and 

 with the production of the like result. He next offers an explana- 

 tion and illustration of the fact (which might almost be predicated, 

 d, priori), and adduces some (possible) analogues from the animal 

 kingdom. 



He then seeks to establish a general law — that transverse con- 

 tractions, occurring in a closed tube filled with fluid, and proceed- 

 ing in one direction only, imply two currents ; a peripheral of ad- 

 vance, taking the same course as the peripheral contractions ; and an 

 axial of return, in the opposite direction. 



He next points out the m.odification of this law for stomachs of 

 human shape, and shows how compatible this is with the careful 

 observations of Beaumont, none of which are essentially opposed 

 to it. 



The author indicates a probable modification correlative with the 

 consistence of the food in some animals, and thus shows a dependence 

 of this physical process on a previous one. 



A solitary experiment is adduced to show that, as in the healthy 

 movement, so also in vomiting, no backward or antiperistaltic con- 

 traction necessarily occurs. 



