24 APPENDIX. 



portant a share 4n the act. Hence it follows, that neither the contraction of the sto- 

 mach alone, nor that of the muscles only, can be sufficient to give rise to the act of vo- 

 miting. It would seem that so intimately connected are inordinate irritations of the 

 stomach with the action of the diaphragm and abdominal muscles, owing to the anato- 

 mical relations of the ganglial system with the eighth pair of nerves, and with those of 

 the spinal cord, that the one can never lake place, under the ordinary state of the sys- 

 tem, without being followed by the other, and giving rise to the act under considera- 

 tion. The nausea which precedes vomiting, is merely the sensible impression made by 

 the irritating cause on the nerves of the stomach, which impression, if sufficiently exalted, 

 terminates in the act in question. When this step of the process is about to take place, 

 the diaphragm is the first to contract in a spasmodic manner ; indeed, the irritation of 

 the stomach having excited the diaphragm, the former is struck by the latter against the 

 abdominal muscles, and at the instant when the diaphragm relaxes, the abdominal mus- 

 cles re-act and impel the stomach against the relaxed and ascending diaphragm, which, 

 in consequence of this state, readily allows the contents of this viscus to be impelled, by 

 the concussion of the abdominal muscles, through the cardia into the oesophagus. That 

 the diaphragm is the first to contract, and that it is the first to relax, are shown by at- 

 tending to the steps of the process, and by the fact that the stomach could not empty 

 itself through the cardia, if the diaphragm were to continue in a state of contraction. 

 It will therefore appear that the action of the stomach is at its acme when the abdominal 

 muscles re-act and consummate the process ; and that, whilst the diaphragm commences 

 the operation, the abdominal muscles are chiefly efficient in perfecting it. It must be kept 

 in recollection that both do not contract at the same time. The violent action of the latter 

 impels the stomach, and, indeed, the superior viscera of the abdomen, so forcibly upon 

 the relaxed diaphragm, and encroaches so much upon the cavity of the thorax, the whole 

 respiratory muscles being then relaxed, that the lungs are at the time considerably pres- 

 sed upon? and this pressure is farther increased by the ascent of the contents of the 

 stomach through the_cesophagus. Hence it is that vomiting always promotes the dis- 

 charge of secretions which have accumulated in the bronchia^. 



HI. Of Human Rumination, -The author has adverted to this subject in the text in a 

 very brief manner. As this affection is more frequently amongst individuals apparently 

 enjoying their usual health than is generally supposed ? and as many who habitually 

 rumiftate consider it to be only a step of the digestive process, which is certainly the 

 truth as far as respects themselves, we shall enter more fully into the subject, as it 

 has more than once fallen under our observation. 



Under the usual circumstances, rumination commences from a quarter of an hour to 

 an hour and a half after a meal. Immediately upon the commencement of this act, a 

 slight sensation of fullness may be felt at the cardia, when the attention is particularly 

 directed to it, that leads to a deeper inspiration than usual. So soon as the act of in- 

 spiration is completed, and while the muscles of the glottis remain fixed, a bolus of the 

 unchanged aliment rises rapidly from the stomach, with the first effort at respiration, 

 at the moment when the diaphragm has just relaxed, and the re-action of the abdomi- 

 nal muscles commenced. But expiration does not take place until the alimentary ball 

 has passed completely into the mouth, as the glottis remains closed until then : upon 

 this having taken place, expiration is immediately effected ; and so rapidly does respi- 

 ration succeed to the regurgitation of the alimentary bolus, that the latter (unless when 

 the attention is closely applied to the subject,) appears as part of the expiratory act. 



The ruminating process is never accompanied, at any time, with the smallest degree 

 of nausea, nor any pain or disagreeable sensation. The returned alimentary bolus is 

 attended with no unpleasant flavour, is in no degree acidulous, and is equally agreea- 

 ble, and is masticated with additional pleasure, and with much greater deliberation 

 than when first taken. 



The whole of the aliments taken at one meal is not returned in order to undergo this 

 process, but chiefly the part that has been insufficiently masticated. 



The more fluid portions are not always returned, unless along with the more solid or 

 imperfectly masticated parts. When, however, the stomach is distended by a large 

 meal, the fluid contents are frequently returned, and subjected to this process 



This affection may be considered as being passively under the control of the will ; 

 and, although it sometimes takes place when the individual is nearly unconscious of 

 the process, yet it never occurs when ttie mind is incapable of being acted on hy ex- 

 ternal impressions received by the senses. Thus, if at any time, from previous fatigue, 

 and the concentration of the organic nervous energy towards the digestive organs, 

 sleep be induced immediately after a full meal, this affection does not take place : but 

 flatulence, acrid eructations, &c. usually supervene, and continue for some time, in 



