1890.] 



The Superior Cervical Ganglion. 



370 



VII. " On the progressive Paralysis of the different Classes of 

 Nerve Cells in the Superior Cervical Ganglion." By J. K 

 Laxgley, F.B.S., Fellow and Lecturer of Trinity College, 

 and W. Lee Dickinson, M.R.C.P., Cains College, Cam- 

 bridge. Received March 15, 1890. 



It is well known that by stimulating the sympathetic nerve in the 

 neck the following effects can be produced : — (1) Retraction of the 

 nictitating membrane ; (2) protrusion of the eyeball and opening of 

 the eye ; (3) turning the eye, if previous to stimulation the optic axis 

 is directed nasally, so that the optic axis is directed straight forwards, 

 or it may be forwards and a little outwards ; (4) dilation of the pupil ; 

 (5) constriction of the small arteries of the ear, conjunctiva, and of 

 various other parts of the head ; (6) in the dog, dilation of the small 

 arteries of the gums, lips, and of some other parts of the head ; 

 (7) secretion of saliva. 



We have shown that the superior cervical ganglion contains nerve 

 cells, interpolated in the course of the nerve fibres concerned in produc- 

 ing all the above effects, and, further, that these nerve cells are readily 

 paralysed by nicotin.* In this paper we consider the question 

 whether the nerve cells are paralysed simultaneously or in a definite 

 order. That different classes of nerve cells are in some cases un- 

 equally affected by nicotin has been already shown by one of us 

 (L., op. cit.), in so far that in the cat the secretory nerve cells on the 

 course of the cervical sympathetic are more readily paralysed than the 

 secretory nerve cells on the course of the chorda tympani ; that in the 

 dog the reverse is the case ; and, lastly, that the nerve cells on the 

 course of the secretory fibres of the chorda tympani are paralysed 

 before those on the course of its vaso-dilator fibres. 



The method employed has been to inject nicotin into a vein, (a) in 

 successive doses, the first dose being rather less than that required 

 to produce complete paralysis of the cervical sympathetic, and to 

 note the order in which the effects normally produced by stimulating 

 the sympathetic disappear; (b) in quantities sufficient to cause com- 

 plete paralysis of the cervical sympathetic, and by stimulating it at 

 short intervals to note the order of recovery of the normal effects of 

 such stimulation. 



Of course, by injecting the alkaloid into the blood, the peripheral 

 nerve endings, as well as the nerve cells of the superior cervical 

 ganglion, are exposed to its action ; but since, as we have shown 



* Langley and Dickinson, 'Roy. Soc. Proc.,' vol. 46, 1889, p. 423; Langley, 

 ' Journal of Physiology,' toI. 11, 1890, p. 146. 



