224 J--N. LANGLEY 



nerves. Tie and eut the sympathetic trunk just below the junction of the 3rd 

 ramus. 



Stimulate with a weak tetanising current the central end of the eut limb of the 

 annulus. — There was a slow but distinct rétraction of the nietilating membrane, 

 and opening of the eye; but no effect on the pupil, on the vessels of the ear or on 

 the hairs of the head. 



ica 



stimulate the thoraeie sympathelic just below the ganglion stellatum; — ail 

 the usual effects were produced in the head, the fore-foot, and the hairs. 



Paint the ganglion stellatum freely with 0.5 per cent nicotine. 



Stimulate the central end of the ventral limb of the annulus; — there was a 

 movement of the nictatating membrane and eyelids as at first. 



Stimulate the thoraeie sympathetic just below the ganglion stellatum, — the 

 usual effects were produced in the head, but no sécrétion or pallor of the fore foot 

 and no movement of hairs in the lower part of the neck and thorax. 



Paint the superior cervical ganglion with 0.5 per cent nicotine ; after this, sti- 

 mulation neither of the annulus of Vieussens nor of the thoraeie sympathetic 

 below the ganglion stellatum produced any effect.- 



Since then the local application of nicotine to the ganglion stellatum 

 does not stop the " reflex ", we must conclude either that it is the only 

 reflex of its kind in the whole sympathetic cliain, which seems to me to be 

 absurd, or that the cells of the ganglion stellatum play no part in it. 

 I hâve said that the nerve-cells of the superior cervical ganglion do take a 

 part in the reflex, so that the diagram (fig. 1), may be taken as representing 

 the meclianism. A nerve fibre divides in the thoraeie sympathetic, sends 

 one branch down one limb of the annulus of Vieussens, and the other brandi 

 down the other limb; on stimulating the central end of one branch, the 

 nervous impulses spread to the other branch and so to the periphery. Such 

 an action we may speak of as a pseudo-reflex action. 



[ may point ont that on the very probable view that a nerve impulse set 

 up in the peripheral end of a sensory fibre passes direct to the spinal cord 

 without passing through the nerve-cell connected with the fibre in the 



