232 DIGESTION. 



mated towards the pylorus. The movements were observed 

 to increase in rapidity as the process of 'chymification advanced, 

 and were continued until it was completed. 



The contraction of the fibres situated towards the pyloric 

 end of the stomach seems to be more energetic and more de- 

 cidedly peristaltic than those of the cardiac portion. Thus, 

 Dr. Beaumont found that when the bulb of the thermometer 

 was placed about three inches from the pylorus, it was tightly 

 embraced from time to time and drawn towards the pyloric 

 orifice for a distance of three or four inches. The object of 

 this movement appears to be, as just said, to carry the food to- 

 wards the pylorus as fast as it is formed into chyme, and to 

 propel the chyme into the duodenum ; the undigested portions 

 of food being kept back until they are also reduced into 

 chyme, or until all that is digestible has passed out. The ac- 

 tion of these fibres is often seen in the contracted state of the 

 pyloric portion of the stomach after death, when it alone is 

 contracted and firm, while the cardiac portion forms a dilated 

 sac. Sometimes, by a predominant action of strong circular 

 fibres placed between the cardia and pylorus, the two por- 

 tions, or ends as they are called, of the stomach, are separated 

 from each other by a kind of hour-glass contraction. 



The interesting researches of Dr. Brinton have clearly es- 

 tablished that, by means of this peristaltic action of the mus- 

 cular coats of the stomach, not merely is chymified food 

 gradually propelled through the pylorus, but a kind of double 

 current is continually kept up among the contents of the stom- 

 ach, the circumferential parts of the mass being gradually 

 moved onward towards the pylorus by the peristaltic contrac- 

 tion of the muscular fibres, while the central portions are pro- 

 pelled in the opposite direction, namely, towards the cardiac 

 orifice ; in this way is kept up a constant circulation of the 

 contents of the viscus, highly conducive to their free mixture 

 with the gastric fluid and to their ready digestion. 



These actions of the stomach are peculiar to it and indepen- 

 dent. But it is, also, adapted to act in concert with the ab- 

 dominal muscles, in certain circumstances which can hardly 

 be called abnormal, as in vomiting and eructation. It has 

 indeed been frequently stated that the stomach itself is quite 

 passive during vomiting, and that the expulsion of its contents 

 is effected solely by the pressure exerted upon it when the ca- 

 pacity of the abdomen is diminished by the contraction of the 

 diaphragm, and subsequently of the abdominal muscles. The 

 experiments and observations, however, which are supposed to 

 confirm this statement, only show that the contraction of the 

 abdominal muscles alone is sufficient to expel matters, from an 



