OF DIGESTION, 25 



consequence of the vital energy and gastric juices being insufficient to the production 

 of the requisite changes on the ingesta retained in a state of imperfect division. 



With respect to the nature of human rumination it appears evident that it only takes 

 place when the vital energy of the assimilating organs is greatly diminished ; conse- 

 quently, when the activity of the stomach, both as it relates to its'muscular action and 

 secreting functions, is equally lessened ; this is apparent from the circumstance, that 

 aliments, if they be taken even in very moderate quantity, are not properly digested by 

 ruminating individuals when they are retained without having been re-submitted to 

 mastication. Connected, also, with debility of the stomach, an increase of its sensibi- 

 lity, which it derives from the distribution of the eighth pair of nerves, seems to*be 

 present. Both these states of this organ render it more necessary that the ingesta 

 should undergo a perfect mastication and thorough admixture of the salivary juices, in 

 order to suit it to the weakened functions of the stomach. 



Under the circumstances of deficient vital energy of the stomach, of increased sensi- 

 bility, and diminished secretion, a small portion only of food can be digested ; yet it is, 

 nevertheless, generally taken in considerable quantity by ruminating* individuals. In 

 this case, that portion of it most favourable to the admixture having combined with the 

 gastric juices, and being, by the natural action of the stomach, conveyed to the pylorus, 

 the undigested portions and those which have been imperfectly masticated, must either 

 remain at the cardiac extremity, or be propelled there by the usual action of the viscus, 

 where they excite its organic sensibility, and, in consequence of intimate nervous con- 

 nection, the co-operation of the muscles of respiration, especially of the diaphragm and 

 abdominal muscles, and thus give rise to the ruminating process. 

 fin its performance, the organic contractility of the stomach can do no more than by au 

 elective process (soon to be explained) place the aliments about to be returned in a 

 situation, in respect to the cardia, favourable to the excitation of the organic sensibility 

 of this organ, and to its ready regurgitation and propulsion along the oesophagus. As 

 soon as the demand is made upon the sensibility by the situation of the alimentary 

 bolus, the par vagal class of nerves is excited to action, and a full respiration is effected, 

 as has been described. The introduction of the bolus into the cardiac extremity of the 

 oesophagus, may be considered as effected by the ordinary contractility of the stomach ; 

 perhaps sympathetically heightened at the moment by the re-action of the abdominal 

 muscles ; while, at the same time, the diaphragm has just undergone relaxation, in 

 which the cardia may, from intimate nervous communication, also participate, and thus 

 facilitate the ascent of the alimentary ball in the cesophagus, which immediately con- 

 tracts behind it from the irritation produced by its passage, and the bolus is thus con- 

 veyed to the mouth. 



That relaxation of both the diaphragm and cardiac extremity of the cesophagus ac- 

 tually exists at the moment, although the glottis still remains closed, appears confirm- 

 ed, both by the period of the respiratory act at which this process is produced, and by 

 the circumstance that, when any restraint is exercised over this affection, it is princi- 

 pally by means of exciting the diaphragm to a frequent and continued action, when the 

 premonitory sensation is felt at the cardia. 



The influence of the will appears to be requisite, since the process is interrupted 

 during sleep. But this influence is only passively engaged in the production of the ru- 

 minating act, by bringing about the co-operation of the respiratory organs. 



The elective process exercised by the stomach in this affection, is similar to that 

 which it exerts in periods of health, which may be considered as relative to the degree 

 of digestive energy, and to the comparative states of comminution and insalivation, in 

 v/hich the various ingesta may enter the stomach. 



During the process of digestion, contraction takes place irregularly and under various 

 situations in this organ, according as different portions of the longitudinal or circular fi- 

 bres may act ; this operates in producing a degree of arrangement in the aliments ; 

 and, as the gastric juices combine with the more soluble portion of the food, especially 

 that situated towards the mucous surface of this organ, which, when duly effected, is 

 conveyed by the varying organic contractility of the muscular coat, towards the pylo- 

 rus ; while a successive and concentric stratum comes in contact with, and, if in a per- 

 meable state from its previous comminution and admixture with the salivary juices, is 

 soon penetrated by the secretions of this organ ; and even the central mass not unfre- 

 quently is obliged to yield its more fluid parts to the exterior layer, when there is a de- 

 ficiency of fluids in the alimentary contents. Hence the not unusual necessity for drink 

 that takes place as digestion proceeds.. In the course of this process, as it is the result 

 of the healthy functions of the organ, the chyme in contact with its mucous surface i.s 

 conveyed in a direction from the cardia to the pylorus. But, if the propagation of th- 

 digested contents towmls this extremity of the organ proceed faster than it can pa?3 



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