572 DIGESTION. 



ramify upon the digastric and stylo-hyoid muscles, and upon the muscles 

 of the lower part of the face ; and probably some of the branches of 

 the cervical plexus, which unite themselves to the descendens noni. It 

 must be admitted, however, that this part of the physiology of deglu- 

 tition is obscure. 1 



Some individuals are capable of swallowing air; and, according to M. 

 Magendie, 2 it is an art that can be attained by a little practice. In the 

 stomach, the air acquires the temperature of the viscus, becomes rarefied, 

 and distends the organ; exciting, in some, a feeling of burning heat; 

 in others, an inclination to vomit, or acute pain. He thinks it pro- 

 bable, that its chemical composition undergoes change; but, on this 

 point, nothing certain is known. The time of its stay in the stomach 

 is variable. Commonly, it ascends into the oesophagus, and makes its 

 exit through the mouth or nostrils. At other times, it passes through 

 the pylorus, and diffuses itself through the whole of the intestinal canal, 

 as far as the anus, distending the abdominal cavity, and simulating 

 tympanites. M. Magendie refers to the case of a young conscript, who 

 feigned the disease in this manner. 



e. Chy unification. 



When the food has experienced changes impressed upon it by the 

 preceding process, it reaches the cavity of the stomach, where it is re- 

 tained for several hours, and undergoes another portion of the digestive 

 action, being converted into a pultaceous mass, to which the term chyme 

 has been applied; whilst the process has been called chymification. It 

 does not seem, that all physiologists have employed these terms in this 

 signification; some have confounded chyle with chyme; and chylification 

 with chymification. The former of these processes is distinctly an in- 

 testinal act: the latter is exclusively gastric. 



The aliment, as it is sent down by repeated efforts of deglutition, 

 descends into the splenic portion of the stomach without difficulty, as 

 regards the first mouthfuls. The stomach is but little compressed by 

 the surrounding viscera, and its parietes readily separate to receive the 

 food; but when it is taken in considerable quantity, the distension gradu- 

 ally becomes more difficult, owing to the compression of the viscera 

 and the distension of the abdominal parietes. The accumulation takes 

 place chiefly in the splenic and middle portions. Dr. Beaumont 3 ob- 

 served, that when a piece of food was received into the stomach, the 

 rugae of the latter gently closed upon it ; and if it were sufficiently fluid, 

 gradually diffused it through the cavity of the organ, but entirely ex- 

 cluded more whilst the action continued. The contraction ceasing, 

 another quantity of food was received in the same manner. It was 

 found, in the subject of his experiments, that when the valvular portion 

 of the stomach, situate at the fistulous aperture, was depressed, and 

 solid food introduced, either in large pieces or finely divided, the same 

 gentle contraction or grasping motion took place, and continued for 

 fifty or eighty seconds, and it would not allow of another quantity, until 



1 Longet, Traite de Physiologic, ii. 334, 337, Paris, 1850. 



2 Carpenter, Human Physiology, ii. 146. 3- Experiments, &c., on the Gastric Juice, p. 110. 



