ABSORPTION. 635 



acts of deglutition, each of which was accompanied by a noise, that 

 seemed to be owing to the passing back of air." 



On the whole, we are, perhaps, justified in concluding, that the 

 ancient doctrine regarding vomiting is full of error, and ought to be 

 discarded ; that the inverted action of the stomach, although not ener- 

 getic, is necessary, that the pressure, exerted on the parietes of the 

 stomach by the diaphragm and abdominal muscles, is a powerful cause, 

 and that the more or less complete paralysis of the diaphragm, or 

 destruction of the abdominal muscles, renders vomiting more feeble 

 and more slow in manifesting itself. The deep inspiration preceding 

 the act of vomiting, is terminated by the closure of the glottis: after 

 this the diaphragm cannot move without expanding or compressing the 

 air in the lungs. It, consequently, presents a resisting surface, against 

 which the stomach may be pressed by the contracting abdominal mus- 

 cles. The order of the phenomena seems to be as follows. The brain 

 is affected directly or indirectly by the cause exciting vomiting ; 

 through the brain and medulla, the glottis is closed, and the diaphragm 

 and abdominal muscles are thrown into appropriate contraction, and 

 press upon the stomach; this organ probably contracts from the 

 pylorus towards the cardia; and, by the combination of efforts, the 

 contents are propelled into the oesophagus, and out of the mouth. 

 These efforts are repeated several times in succession, and then cease, 

 to reappear at times. Whilst the rejected matters pass through the 

 pharynx and mouth, the glottis closes ; the velum palati rises and be- 

 comes horizontal as in deglutition ; but owing to the convulsive action 

 of the parts, these apertures are less accurately closed, and more or 

 less of the vomited matter passes into the larynx or nasal fossae. On 

 account of the suspension of respiration impeding the return of blood 

 from the upper parts of the body, and partly owing to the force with 

 which the blood is sent through the arteries, the face is flushed, or 

 livid, the perspiration flows in abundance, and the secretion of tears is 

 largely augmented. 



CHAPTER II. 



ABSORPTION. 



IN the consideration of the preceding functions, we have seen the 

 alimentary matter subjected to various actions and alterations ; and at 

 length, in the small intestine, possessed of the necessary physical con- 

 stitution for the chyle to be separated from it. Into the mode in which 

 this separation, which we shall find is not simply a secerning action, 

 but one of vital elaboration, is effected, we have now to inquire. It 

 constitutes the function of absorption, and its object is to convey the 

 nutritive fluid, formed from the food, into the current of the circula- 

 tion. Absorption is not, however, confined to the formation of this 

 fluid. Liquids can pass into the blood directly through the coats of 

 the containing vessel, without having been subjected to any elabora- 

 tion; and the different constituents of the organs are constantly sub- 



