188 Prof. J. N. Langley. On Nerve Endings and on [May 24, 



which the limbs were placed. Ifc is noteworthy that this cataleptic condition 

 is abolished by a sufficient dose of curari. 



Nerve Endings in Nerve Cells. 



Evidence of a similar nature to that which I have given for the relation 

 of motor nerves to striated muscle exists also for the relation of the nerve- 

 fibres which run from the spinal cord (pre-ganglionic fibres) to end in con- 

 nection with sympathetic nerve cells. 



The action of nicotine on sympathetic nerve cells* is very similar to that 

 which it has on the gastrocnemius muscle of the fowl. It stimulates nearly 

 all the sympathetic nerve cells of the body, and in larger dose, varying in 

 different cases, it abolishes the effect of stimulating the pre-ganglionic 

 nerves, i.e., it paralyses the nerve-fibres. 



Curari in large amounts paralyses the pre-ganglionic fibres, the amount 

 required varying with different classes of sympathetic fibres ; when it does 

 this it prevents a normally effective amount of nicotine from causing any 

 stimulation. 



Now nicotine has as strong a stimulating effect on the sympathetic 

 ganglia after degeneration of the pre-ganglionic fibres as it has normally. 

 There is no suggestion of the existence of any structure in connection 

 with the nerve endings which could keep them intact after section of the 

 nerves from which they arise, and I conclude that they degenerate after 

 nerve section. 



Eam6n y Cajal, Dogiel, Huber, and others, who have used either Golgi's method or 

 Ehrlich's methylene blue method for staining nerve endings, find that the nerve-fibres 

 running to a sympathetic ganglion are not continuous with the nerve cells, but end free 

 in close contact with them. I have obtained similar results by the methylene blue 

 method. Anderson (' Journ. of Physiol.,' vol. 28, p. 499, 1902) gives one piece of experi- 

 mental evidence for continuity. He finds that in very young animals delay of develop- 

 ment of myelin in the cervical sympathetic nerve-fibres occurs not only on section of the 

 nerve itself, but also on section of the post-ganglionic fibres of the superior cervical 

 ganglion. The latter fact, he considers, shows continuity through the nerve cells of pre- 

 and post-ganglionic fibres. It is certain, however, that developing nerve-fibres are much 

 more influenced by injuries than the fully formed ones ; and it is possible that the 

 atrophy of the nerve cells caused by cutting the post-ganglionic fibres in very young 

 animals injures the nerve endings in close contact with them, and in this case the section 

 of the post-ganglionic fibres is practically equivalent to section of the pre-ganglionic 

 fibres. 



Some evidence against continuity is given by the fact that nicotine applied to a 

 ganglion causes no axon reflex ; i.e., the stimulus set up in the nerve cells does not pass 

 back to the nerve-fibres. How much weight is to be attached to this depends upon the 

 nature of the nervous impulse about which at present there is doubt. But the fact is, I 



* Cf. Langley, 'Journ. of Physiol.,' vol. 27, p. 224, 1901. 



