LIFE AND WRITINGS OF ROBERT WHYTT, M.D. 125 



the voluntary muscles, owing to acrimony affecting the mucous membrane of the 

 stomach or bowels, from the simple transitory cramp of the calf of the leg, the 

 result of acid in the stomach, to the violent cramps over the body in the irrita- 

 tion of Asiatic cholera. The dilatation of the pupil from irritation of the bowels 

 may seem to take place through a ganglion of the sympathetic system, since the 

 radiated muscular fibres of the iris are believed to be supplied with nerves from 

 the sympathetic. 



But with respect to sympathetic sensations, like the pain of the sole of the 

 foot from an ulcer in the bladder, pain in the cheek and side of the head from a 

 carious tooth, Whytt doubtless says correctly, that they do not depend on con- 

 nections of nerves with each other in their course ; nevertheless, there is some 

 reason to think that such sympathies may depend on the proximity of the con- 

 nections of the nervous fibrils concerned at the nervous centre. Thus Muller 

 has remarked, that there is what he calls a radiation of sensation, by which 

 nervous fibrils adjacent in their connection with the nervous centre to that by 

 which an impression is brought thither are similarly afiected, so that the sensa- 

 tion is spread not only to the peripheral extremity of the recipient of the impres- 

 sion, but also to the peripheral extremities of all the adjacent fibrils involved at 

 their origin, however distant their peripheral extremities may be from that of the 

 recipient. Thus, if the afferent fibrils from the upper surface of the liver termi- 

 nate in the nervous centre near the termination of afferent fibrils from the top of 

 the shoulder, a strong impression conveyed through the former will radiate its 

 effect to the adjacent origins of the latter, so as to cause the patient to refer that 

 impression not only to the liver, but also to the top of the shoulder. This 

 explanation gains probability both from the experiments made as to nervous 

 induction, and also from the rule laid down by Sir William Hamilton, that a 

 sentient nervous fibril does not supply a distinct knowledge of the seat of the 

 impression conveyed by it, unless when that impression is moderate ; while in 

 proportion as the impression is strong, the knowledge given of its seat is vague. 



Whytt does not indeed suggest this explanation, but he makes a near 

 approach to it, when he says that " the impressions made by the stars by day 

 on the retina are sutibcated and lost in those stronger ones made by the illu- 

 minated atmosphere." Supplemented, then, by this idea of the radiation of strong 

 impressions, Whytt's doctrine of sympathetic sensations seems to include all 

 that is at present known on this subject. The late Professor Alison published in 

 the " Transactions of the Medico-Chirurgical Society of Edinburgh" an excellent 

 commentary on Whytt's doctrine of sympathy. 



The work itself, the preliminary dissertation to which has just been com- 

 mented on, while it is in every respect worthy of Whytt's reputation, is hardly 

 of a nature to bear an analysis in a memoir like the present. His illustrations 

 of the symptoms of nervous diseases are given with a masterly hand. Thej/ 



