OF DIGESTIOK. 23 



Conformably to the inferences stated, (in note H. of the Appendix) we consider that, 

 whatever may be the order in which the ingesta pass the pylorus into the smaller in- 

 testines, the digestive process in the stomach, and, indeed, throughout the alimentary 

 canal, is more immediately the result of the vital influence with which the stomach and 

 intestines are endowed, than of the solvent properties of the gastric juice. We, how- 

 ever, by no means would be understood to deny that these properties are requisite to 

 the process, we only contend that they are subordinate to the manifestation of vitality 

 exerted by the stomach, and that the vital influence of this viscus is chiefly concerned 

 an its performance. The digestive process, whether that part of it which is performed 

 in the stomach, or that which is accomplished by the small intestines, appears to be es- 

 sentially a vital process, whether we view it in man or in any of the lower animals. 

 Every theory, therefore, which excludes its immediate operation, must be defective. 

 Conformably to this view, it must be supposed to vary in activity, as indeed we ac- 

 tually find that it does, according to the state of the vital influence with which the 

 organs concerned in its accomplishment are originally endowed, and according to the 

 state and distribution of this influence with which the organs concerned in its accom- 

 plishment are originally endowed, and according to the state and distribution of this 

 this influence throughout the organs and textures at the time when this process 

 is going forward. We do not deny that the influence which we impute to the 

 stomach, is one which is not intimately connected with the gastric juices ; on the 

 contrary, we believe that they are the medium through which it acts; in short, 

 that, owing to the abundant supply of nerves which this viscus receives, chiefly from 

 the ganglionic system, it possesses a considerable share of the vital influence of the 

 body ; that this influence is chiefly exerted in giving rise to its organic motions, and in 

 producing its specific secretions, and that, from the circumstance of so large a propor- 

 tion of its ganglial nerves being distributed on its arteries, the juices which they se- 

 crete or exhale are imbued with an emanation or some certain manifestation of this in- 

 fluence, which is the principle agent in the digestive process. Hence the relation be- 

 tween the states of this influence, and the quantity and quality of the gastric juices must 

 be very intimate; and it seems to be owing to this intimacy, that the primary agent has 

 been hitherto overlooked in the more evident and grosser materials with which it is al- 

 lied, and by means of which it operates. The varying conditions of the function of di- 

 gestion in health and in disease, and the close connexion between it and every manifes- 

 tation of the body, eminently support this view of the subject ; and, independently of 

 the direct evidence fnrnished by the very interesting experiments of Drs. Wood and 

 Sillar, of Liverpool, many collateral proofs may be adduced in its behalf. 



H. Of Vomiting. W^hilst we attribute the digestive process chiefly to the vital influ- 

 ence proceeding from the ganglial system, we do not overlook the fact that that part of 

 this system supplying the stomach is acted upon, to a certain extent, through the me- 

 dium of nerves communicating with, and of others given off from, the cerebro-spinal 

 system, which may reasonably be supposed to perform the functions belonging to their 

 respective sources. 



It is owing to this provision, when the stomach is irritated, and when its organic con- 

 tractility is inordinately excited, that its sensibility is also roused the influence is pro- 

 pagated to the sensonmn, and contraction of the abdominal and respiratory muscles is 

 also produced, which contracting co-operates with that of the stomach itself, in giving 

 rise to vomiting. Magendie has inferred from his experiments, that it is only the con- 

 traction of the abdominal muscles and diaphragm which produces vomiting, and that 

 the stomach has no share in the act. This physiologist, on this, as on other occasions, 

 has not taken into account the various sources* of error to which experiments on living 

 animals are liable. He has not sufficiently considered, or calculated upon, the unna- 

 tural positions in which such experiments place the animals experimented upon, and 

 thus derange their natural operations. Stricter and more comprehensive views of the 

 subject show that, whilst former physiologists have erred in attributing the act of vo- 

 miting too exclusively to a sudden contraction of the stomach, Magendie and his disciples 

 have been equally to blame in adopting too implicitly the more tangible phenomenon 

 of some inconclusive experiments. The steps in this'process appear to be the follow- 

 ing: an irritating cause rouses the organic insensibility of the stomach, and gives rise 

 to a considerable contraction of its muscular coats. This exalted state of its organic 

 sensibility and contractility excites, in consequence of the intimate nervous communica- 

 tion between the stomach on the one hand, and the diaphragm and abdominal muscles 

 on the other*, the action of the latter, which, from vicinity of situation, perform so im- 



* Through the medium of the eighth pair of nerves, and of the branches of the gan- 

 glia! system which joins the spinal nerve?* 



