380 Mr. J. N. Langley and Mr. W. L. Dickinson. [Mar. 27, 



(op. cit.), even large doses of nicotin* do not prevent the normal 

 sympathetic effect from being obtained on stimulating peripherally 

 of the superior cervical ganglion ; any absence of the normal effect of 

 stimulating the sympathetic in the neck which may be caused by a 

 small dose of nicotin must be due to the action of the alkaloid on the 

 nerve cells of the ganglion. 



The method of injecting nicotin into a blood vessel is preferable to 

 that of applying dilute nicotin to the ganglion itsslf (although this has 

 the advantage of limiting the effect to the ganglion), because of the 

 difficulty of applying the nicotin in such a way as to make certain 

 that equal amounts reach all the nerve cells ; by the latter method it 

 might be possible for the external cells of the ganglion to be paralysed 

 and the internal cells to have escaped paralysis. 



In the course of our experiments we have naturally had frequent 

 occasion to observe the effect of stimulating the sympathetic upon the 

 blood supply of the lips and gums. It will be convenient to discuss 

 this action before proceeding to the more immediate object of our 

 experiments. 



Effect of Stimulating the Sympathetic upon the Bucco-labial Region. — 

 The discovery in the sympathetic of the dog of vaso-dilator fibres for 

 the lips, gums, and of some other parts of the head is due to Dastre 

 and Morat. f The whole region in which dilation is produced they 

 call the bucco-facial region ; this includes the mucous membrane of 

 the nose, hard palate, of the gums, lips, and the neighbouring 

 cutaneous regions. On the other hand, the same stimulus produces 

 constriction of the small arteries in the epiglottis, tonsils, and soft 

 palate. Bochefontaine and Vulpian^ observed, that sometimes the 

 dilation was preceded by a constriction. Dastre and Morat§ later 

 found a similar constriction ; they state that it occurs only with a 

 certain strength of current, which is a little less than that required 

 to produce primary dilation, so that, when electric shocks cause con- 

 striction before the dilation, no effect is produced if the shocks are 

 made a little weaker, and primary dilation is produced if they are 

 made a little stronger. 



In our experiments, the variation in the strength of the shocks 



* In a recent experiment upon a rabbit 1450 nigra, of nicotin were injected into a 

 vein without causing the heart to stop. Stimulation of the filament running from 

 the superior cervical ganglion to the internal carotid, i.e., stimulation of the sympa- 

 thetic peripherally of the ganglion, still caused dilation of the pupil. As the experi- 

 ments in this paper show, 5 to 10 mgm. of nicotin are sufficient to prevent stimulation 

 of the sympathetic in the neck, i.e., of the sympathetic centrally of the ganglion, 

 i rom producing any effect on the pupil. 



f Dastre and Morat, ' Comptes Rendus de l'Acad. des Sciences,' vol. 91, 1880, 

 pp. 393 and 441. 



X Bochefontaine and Vulpian, ' Soc. de Biologie,' 1880, p. 319. 



§ Dastre and Morat, ' Le Systeme Nerveux Vaso-Moteur' (Paris), 1884, p. 180. 



