706 PHYSIOLOGY IN RELATION TO 



can be kept up, and will, like the muscular irritability, persist in a 

 decapitated animal for a long while after death, if artificial respira- 

 tion be put in play. The empty state of the arteries post mortem is 

 most probably to be explained by the action of the peripheral 

 nerve-system on the arterioles ; though Dr. Alison would have 

 explained it by the attraction a fronte force of the tissues around 

 the capillaries ; but Von Bezold's view of the source of the nervo- 

 muscular action of the peripheral vessels is, I apprehend, more 

 untenable and less plausible than most theories which have ' had 

 their day and ceased to be.' 



The following short history seems to me to be a good instance of 

 the action, or rather of the want of action, of the peripheral nerve- 

 system upon the arterioles. A man, who came some years ago 

 under my own care, had had a bullet pass through his arm just 

 above the elbow, so as to sever the musculo-spiral nerve. The 

 scars of exit and entrance were in the lower third of the arm. 

 Under ordinary circumstances, the soft parts of the lower arm 

 maintained their normal consistence ; but their power of resisting 

 changes of temperature was greatly impaired, as well of course as 

 the sensibility of the parts supplied by the injured nerve. I recol- 

 lect seeing the swollen state of the inner side of the hand one cold 

 raw morning when the man was on sentry duty, and had his hand 

 chilled down by the musket he had to carry. Now, I apprehend 

 that this turgescence is to be explained by saying, that the local or 

 peripheral nerve- system of the affected parts was competent under 

 ordinary circumstances to regulate the calibre of the arteries ; but 

 that its activity was liable to be depressed, as under the circum- 

 stances related, into actual abeyance, in the absence of any possi- 

 bility of any assistance being supplied to it from the cranio-spinal 

 nerve-axis. Thus, under the depressing effect of cold, which seems 

 to work here much as it does in checking the regeneration of 

 artificially amputated parts in snails and in salamanders (' Miiller's 

 Physiology,' by Baly, 2nd edit., i. p. 444 ; Bonnet, ' CEuvres,' torn. 

 V. i. pp. 328, 329), the peripherally placed ganglionic system was 

 put into abeyance ; and turgescence of the vessels it ordinarily 

 supplied with ' tone ' ensued. Just similarly in mammals the skin 

 of which has been covered with an impermeable varnish, and 

 in which death is as much due to the chilling down which the 

 destruction of the non-conducting power of their hairy integument 



