BBOWW-SEQTJABD ON THE CENTIME NEBTOTTS SYSTEM - . 285 



phenomena connected with nutrition, secretion, animal heat, &c. which 

 are now regarded as being under the control of the vaso-motor system 

 of nerves. It would be impossible, within the limits of an article such 

 as this, to give even a resume of the many important facts, the disco- 

 very of which has given a sanction to the views of many eminent 

 physiologists, which, it must be confessed, was needed : and indeed, 

 it is not possible to do more than allude to some of the leading hypo- 

 theses which have of late been put forward, with reference to the 

 influence of the entire nervous system upon blood-vessels, or (as we 

 have already stated in more general terms) , upon involuntary muscular 

 fibre, whether in the heart, blood-vessels, intestines, or elsewhere. 



One of the hypotheses in question appear to us as novel and start- 

 ling, as it does speculative and untenable, and were it not that it is 

 associated with the name of one of the most eminent experimental phy- 

 siologists in Europe, it would hardly call for even a passing mention. 

 Professor Bernard has imagined, that the dilatation of the blood- 

 vessels in many of the circumstances influencing secretion, &c. is an 

 active phenomenon ; he fancies, in fact, that the capillaries have two 

 properties, contraction and dilatation, and, if we understand him aright, 

 he conceives the latter to be no less an active phenomenon than the 

 former, each being put into play by a distinct set of nerves. On the 

 other hand, to say that the blood-vessels dilate in consequence of a 

 greater attraction for arterial blood developed in the tissues of the 

 part, conveys to our mind no distinct meaning, but is merely putting 

 into other, and less simple, terms the expression of what takes place 

 when the small arteries are observed to become dilated. The view ad- 

 vocated by Pfliiger, (Ueber das Hemmungs Nerven- system), must be 

 admitted as exceedingly ingenious, and as giving a very adroit expla- 

 nation of many of the phenomena in question ; but we cannot but 

 agree with Mr. Joseph Lister, that the supposition, that there is a 

 certain set of nerve fibres, the so-called inhibitory system of nerves 

 (Hemmungs Nerven-system) whose sole function is to arrest, or keep 

 a check upon, action, seems a very startling innovation in physiology, 

 and one which we must be very cautious about accepting, so long as 

 the same phenomena may be accounted for by the supposition of a more 

 simple, comprehensive and uniform action in those nerve fibres, which 

 seem to preside over the movements of involimtary muscles. Indeed, 

 we cannot help looking forward to a further development of the 

 notions shadowed forth by Lister, that the peripheral expansions, 

 (ganglia and nuclei, &c.) of the nervous system are in all cases essen- 

 tial to these contractions of vessels, &c. and while capable of inde- 

 pendent action, are nevertheless susceptible of being stimulated or 

 checked by the governing influence of the central nervous system ; 

 the so-called inhibitory influence being due to the more or less ener- 

 getic operation of the same nerve fibres, and bearing a remote analogy 

 with that almost, if not entirely, passive condition of the nervous 

 system, which gives rise to muscular tonicity. 



But to pass from the realms of hypothesis, it appears tolerably 



