851 



SYMPATHY. 



of others. The penis, the beard, the vocal 

 organs, experience a marked increase of de- 

 velopment at the adult period of life simul- 

 taneously with the enlargement of the testes ; 

 and, it may be added, in effect of their increase, 

 because the early removal of these organs pre- 

 vents the growth of the others. And so like- 

 wise as the ovaria are developed, the uterus, 

 the vulva, the mamma,-, increase in size ; the 

 ovarian and uterine irritation which accom- 

 panies the menstrual flux causes enlargement 

 of the breasts, which subsides as soon as that 

 period has gone by. 



The various examples enumerated in the 

 preceding paragraphs may be classed under 

 three heads : first, sympathies between dif- 

 ferent individuals ; secondly, those which affect 

 the mind, and, through it, the body ; and, 

 thirdly, those which are strictly organic, and 

 therefore physical. 



Of the first class of sympathies we can offer 

 no physical explanation. Whether the ner- 

 vous system of one individual can directly 

 affect that of another, or whether the effect 

 is produced on the imagination, and after- 

 wards on the nervous system, are questions 

 still sub jmlicc. The serpent fascinates his 

 prey, apparently by the power of his eyes, 

 and it is well known that one man can exert 

 a marked control over another by a mere 

 look ; and in the same way man can control 

 other animals, even the fiercest carnivora, by 

 a firm and decided glance of the eyes. It is 

 no explanation of sympathetic phenomena of 

 this kind to ascribe them to the effect of a 

 tendency to imitation. Imitation is voluntary; 

 these actions are involuntary, or take place 

 even in despite of the will.* 



In the second class of sympathetic pheno- 

 mena, an affection of the mind is a necessary 

 link. But why that affection of the mind 

 should produce its peculiar effect is a question 

 difficult to solve. Why should the perception 

 of certain odours produce in one case in- 

 creased action of the salivary glands, and in 

 the other case cause syncope ? The only reply 

 which can be made to this question is, that in 

 these instances the impression on the senso- 

 rium causes a change there analogous to that 

 which an original affection of the mind of 

 similar kind would produce, and therefore 

 gives rise to effects of the same nature as 

 those resulting from that mental change. 



O O 



Thus the smell of savoury food excites in the 

 mind the idea of food, which in a hungry man 

 would, if it occurred spontaneously, occasion 

 a flow of saliva. And the odour which oc- 

 casions syncope, creates in the mind an emo- 

 tion of disgust, which, if it arose independently 

 of the physical impression, would affect the 

 heart through the centre of emotion. It is 

 plain, however, that that portion of the ner- 

 vous centre which is affected in such cases, 

 must have a direct influence upon the parts 

 in which the sympathetic phenomena appear; 

 and this through commissural fibres, or the 

 continuity of its gray matter with that of the 

 centre from which its nerves immediately 

 spring; thus, in the instances referred to, the 

 * Bostock's Physiology, vol. iii. p. 227. 



centre of sensation, which is first affected, is, 

 through the medulla oblongata, connected with 

 the salivary glands by the fifth nerve, and with 

 the heart by the vagus. 



We derive an explanation of the third 

 class of sympathetic phenomena from the 

 known laws of sensitive and motor nerves. 

 It is known that stimulation of a sensitive 

 nerve at its origin, or in any part of its course, 

 will give rise to a sensation which will be re- 

 ferred to the peripheral extremity of the sti- 

 mulated fibres ; and that a stimulus applied to 

 a motor nerve causes a change in it which 

 spreads peripherad from the point stimulated, 

 and therefore affects the muscular parts with 

 which it is connected. It is known also, that 

 a sentient nerve may excite a motor or sensi- 

 tive nerve which is implanted near to it in 

 the nervous centre doubtless through the 

 change which it produces in that centre ; nor 

 can it be doubted that a sensitive nerve may 

 receive such a powerful stimulus as to exalt 

 the polar force of a large portion of the 

 nervous centre in the neighbourhood of its 

 insertion, and thus to excite a similar change 

 in all the nerves, whether motor or sensitive, 

 which are connected with it. Thus, ac- 

 cording to the intensity of the original stimu- 

 lus, there will be a radiation of nervous force 

 from the centre, either in one or two motor 

 or sensitive nerves, or in several such ; and 

 the number and variety of the sympathetic 

 phenomena will thus depend on the intensity 

 and extent of the change in the nervous 

 centre excited by the primary stimulus. 



To explain, then, the phenomena of sensa- 

 tion and motion under consideration, we 

 must determine the individual nerves affected 

 in each instance, and ascertain what con- 

 nexions they have with each other. We 

 learn from anatomical investigation, that, al- 

 though nerves anastomose with each other in 

 their distribution, this anastomosis is by no 

 means of that kind which would justify the 

 supposition that an irritation could be com- 

 municated from one to the other in their 

 course. The nerve-fibres only lie in juxta- 

 position, but do not communicate ; and there 

 is an evident provision in the tubular mem- 

 brane and white substance of Schwann for 

 the insulation of the central axis, which is 

 probably the effective substance in the nervous 

 action. We must seek, therefore, in the 

 nervous centres for such a communication be- 

 tween these nerves as may explain the excita- 

 bility of one by the other. In the present 

 state of our knowledge we can do no more 

 than state it as in the highest degree pro- 

 bable that nerves implanted in the centre im- 

 mediately contiguous to each other can exert 

 an influence upon the vesicular matter of the 

 centre, and upon each other. 



But there are certain facts which demon- 

 strate beyond all doubt, that, in such actions 

 as we refer to, the integrity of the centre 

 forms a necessary condition. First, in many 

 of the instances it is plain that there can be 

 no connexion between the affected nerves 

 elsewhere than in the centre, for they are so 

 distinct from each other that there is not even 



