458 



SYMPATHETIC NERVE. 



to Volkmann, by the different characters ex- 

 hibited by the two. When stimulus acts im- 

 mediately on motor nerve fibres, contraction 

 ensues only in that muscle or part of the 

 muscle to which these are distributed; when 

 it affects the whole trunk of such a nerve, 

 many muscles are excited to contraction ; the 

 contraction so produced, however, is a mere 

 quivering, quite different from the combined 

 and plan-like movements of the muscles of 

 respiration, &c., or those reflex movements 

 which are produced artificially. In these, 

 there is a certain unity and plan, in the others 

 not ; the difference depending on the circum- 

 stance that in the one a regulating principle 

 associates the muscular movements for the 

 attainment of an organic object or purpose ; 

 in the others this does not take place. When 

 the regular and plan-like manner in which 

 the pulsations of a heart removed from the 

 body take place, is compared with the tu- 

 multuous and purposeless quiverings of a 

 diaphragm similarly circumstanced, it is hardly 

 possible to suppose that the two kinds of 

 movement proceed from the same principle. 

 Irritability acted on by the stimulus of the 

 blood, or air, might explain the mere con- 

 traction of the heart; the regular order, how- 

 ever, in which this takes place, implies the 

 existence of a regulating principle ; and a re- 

 gulating principle implies the existence of a 

 regulating apparatus. While the regular 

 movements of the voluntary muscles suddenly 

 cease when the brain and spinal cord are de- 

 stroyed, those of the organic muscles con- 

 tinue;; and hence their regulating apparatus 

 cannot lie in the brain and spinal cord, and 

 can only, therefore, be situated in the ganglia 

 of the sympathetic. 



The heart, according to Volkmann, is 

 more flabby after death than it is during life : 

 the intestines, in like manner, are collapsed in 

 the dead body, and appear like so many flat- 

 tened bands; while in the living body, at least 

 in small animals, they present more the aspect 

 of tubes ; the looseness of the skin and of the 

 scrotum in the dead body is also remarkable, 

 compared with the appearance they present 

 in the living. These differences depend upon 

 a loss of tone. The tone of the involuntary 

 or organic contractile structures does not, 

 however, depend on the brain or spinal cord, 

 inasmuch as it does not cease after these parts 

 have been destroyed, but may continue in the 

 amphibia at least for months thereafter. It 

 depends, according to Volkmann, upon the 

 sympathetic ; and from this he derives another 

 argument in favour of the view that the ac- 

 tivity of the sympathetic or ganglionic nerve- 

 fibres does not depend upon the brain or 

 spinal cord. After division of a motor nerve, 

 the muscles immediately became relaxed, 

 which shows, according to him, 1st, that the 

 tone depends on an active contraction of the 

 muscle ; 2nd, that the mere irritability of the 

 muscle is not alone sufficient for the restoration 

 of this contraction, but also requires an ex- 

 citing cause or motor impulse ; 3rd, that the 

 nerve conveys this motor impulse to the 



muscle; 4th, that the place where this motor 

 impulse arises or originates is not the nerve 

 itself, but is a central organ. If now, after 

 destruction of the brain and spinal cord, the 

 tone in the organic muscles and many other 

 contractile tissues continues, it follows from 

 this that, besides the brain and spinal cord 

 there must still be another centre from 

 which motor impulses proceed, and this can 

 only be the ganglia of the sympathetic. 



In regard to this question, so far as our 

 knowledge of the anatomical constitution of 

 the sympathetic extends, the most probable 

 view would seem to be that it is partly inde- 

 pendent, in its action, of the brain and spinal 

 cord, partly dependent. The circumstance 

 that there are present in its branches nume- 

 rous nerve- fibres which are derived from the 

 brain and spinal cord, would appear to indicate 

 that the organs to which such fibres proceed 

 must be to a certain extent influenced by the 

 central masses of the nervous system. From 

 the circumstance, however, that it probably 

 contains other nerve-fibres which do not arise 

 in the brain and spinal cord, and more particu- 

 larly from the circumstance of gray nervous 

 matter being present in different parts of its 

 extent, it seems not unreasonable to suppose 

 that the influence which it exercises over the 

 parts towhich it is distributed originates, partly 

 at least, not in the brain or spinal cord, but in 

 the gray or ganglionic matter mentioned. If 

 we attribute to the gray matter of the brain 

 or spinal cord a certain property of originating 

 nervous force, it seems unreasonable to deny 

 similar properties to the gray matter occurring 

 in other parts of the nervous system. What- 

 ever properties are possessed by the one, 

 analogous properties are, it is to be expected, 

 possessed by the other. Besides, no other 

 hypothesis which has been proposed to ac- 

 count for the function of the ganglia appears 

 to harmonise so closely with known facts as 

 that which regards them as so many distinct 

 peripherical nervous masses endowed with 

 properties similar to those which are com- 

 monly attributed to a nervous centre. 



Properties of fibres of sympathetic. Sensory 

 properties. In regard to the sensory pro- 

 perties of the sympathetic, different statements 

 are made by authors. Bichat, Magendie, 

 Dupuy,* and others, observed that section of 

 the branches of the sympathetic was attended 

 with few or no signs of pain. Dupuy states 

 that he has removed the superior cervical 

 from the horse without the operation appear- 

 ing to call forth any marked expression of 

 pain. Section of the sympathetic cord in the 

 neck may often be performed in the rabbit 

 without any indication of sensibility being 

 given. Haller found, on the other hand, that 

 irritation of the hepatic plexus in the dog gave 

 rise to distinct signs of pain : the same results 

 were also obtained by Meyer from irritation 

 of the solar plexus. When he made incisions 

 into the superior cervical ganglion, he found, 

 contrary to what had been observed by Dupuy, 



* See Longct. op. cit. torn. ii. 



