FUNCTIONS OF THE PAR VAGUM. 321 



neutral, and at last acquired acidity only from its own transformation into lactic acid. In 

 the stomachs of other dogs after the division of the nerves, he traced the transformation of 

 cane-sugar into grape-sugar in three or four hours; and in ten or twelve hours the trans- 

 formation into lactic acid was complete. In others, when the food was not capable of an 

 acid transformation, it remained neutral to the last. In no case did any part of the food pass 

 through the peculiar changes of chymification. In a last experiment, he gave to each of two 

 dogs, in one of which he had cut the nerves, a dose of emulsine, and half an hour after, a 

 dose of amygdaline (substances which are innocent alone, but when mixed produce hydro- 

 cyanic acid). The dog, whose, nerves were cut, died in a quarter of an hour, the sub- 

 stances being absorbed unaltered and mixing in the blood: in the other, the emulsine was 

 changed by the action of the gastric fluid before the amygdaline was administered, and it 

 survived. Gazette Med., Juin 1, 1844,/rom the Report of the Jicad. dcs Sci., seance du 27 Mai, 

 1844. M. C.] 



a. Another series of experiments was performed by Dr. Reid, for the purpose of testing 

 the validity of the results obtained by Sir B. Brodie, relative to the effects of section of the 

 Par Vagura upon the secretions of the stomach, after the introduction of arsenious acid into 

 the system. According to that eminent Surgeon and Physiologist, when the poison was 

 introduced after the Par Vagum had been divided on each side, the quantity of the pro- 

 tective mucous and watery secretions was much less than usual, although obvious marks of 

 inflammation were present. In order to avoid error as much as possible, Dr. Reid made five 

 sets of experiments, employing two dogs in each, as nearly as possible of equal size and 

 strength, introducing the same quantity of the poison into the system of each in the same 

 manner, but cutting the Vagi in one, and leaving them entire in the other. This comparative 

 mode of experimenting is obviously the only one admissible in such an investigation. Its 

 result was in every instance opposed to the statements of Sir B. Brodie ; the quantity of the 

 mucous and watery secretions of the stomach being nearly the same, in each individual of 

 the respective pairs subjected to experiment; so that they can no longer be referred to the 

 influence of the Eighth pair of nerves. Moreover, the appearances of inflammation were, in 

 four out of the five cases, greatest in the animals whose Vagi were left entire ; and this seemed 

 to be referrible to the longer duration of their lives after the arsenic had been introduced. 

 The results of Sir B. Brodie's experiments may perhaps be explained, by the speedy occur- 

 rence of death in the subjects of them, consequent (it may be) upon the want of suffi- 

 ciently free respiration, which was carefully guarded against by Dr. Reid. 



415. So far as the results of Dr. Reid's experiments may be trusted to, 

 therefore, (and the Author is himself disposed to rely on them almost im- 

 plicitly,) all the arguments which have been drawn in favour of the doctrine 

 that Secretion depends upon Nervous agency, from the effects of lesion of the 

 Vagi upon the functions of the Stomach, must be set aside. That this nerve 

 has an important influence on the gastric secretion, is evident from the defi- 

 ciency in its amount soon after the operation, as well as from other facts. 

 But this is a very different proposition from that just alluded to; and the 

 difference has been very happily illustrated by Dr. R. " The movements of 

 a horse," he observes, " are independent of the rider on his back, in other 

 words, the rider does not furnish the conditions necessary for the movements 

 of the horse; but every one knows how much these movements may be 

 influenced by the hand and heel of the rider." It may be hoped, then, that 

 physiologists will cease to adduce the oft-cited experiments of Dr. Wilson 

 Philip, in favour of the hypothesis (for such it must be termed) that secretion 

 is dependent upon nervous influence, and that this is identical with galvan- 

 ism. Additional evidence of their fallacy is derived from the fact mentioned 

 by Dr. Reid, that the usual mucous secretions of the stomach were always 

 found; and they are further invalidated by the testimony of Miiller, who 

 denies that galvanism has any peculiar influence in re-establishing the gastric 

 secretion, when it has been checked by section of the nerves. 



416. It only remains to notice the influence of section of the Vagi upon 

 the actions of the Heart. It has been asserted by Valentin and other experi- 

 menters, that mechanical irritation of these nerves, especially at their roots, 

 has a tendency to excite or accelerate the heart's action; other experimenters, 

 however, have obtained none but negative results. Admitting, what seems 

 probable, that the Cardiac branches of the Pneumogastric have some influence 



