HuBER, Sympathetic Nervous System. 119 



the injection of a certain dose of nicotin, stimulation of the 

 cervical sympathetic, below the superior cervical ganglion, does 

 not produce dilation of the pupil or constriction of the vessels 

 of the ear, while stimulation of the sympathetic nerve fibers 

 above the ganglion produces these changes in the normal man- 

 ner." This, as they suggest, might be due to the fact that the 

 medullated fibers below the ganglion are paralyzed and not the 

 non-medullated fibers above the ganglion. That the medullated 

 fibers as such are not paralyzed is shown by the fact that, at a 

 time when stimulation of the cervical sympathetic does not 

 cause dilation of the pupil, stimulation of the sciatic causes a 

 normal contraction of the muscles supplied by this nerve. 

 They have, however, offered a much better proof in the follow- 

 ing experiment : 



The cervical sympathetic was exposed and painted with a 

 I % solution of nicotin. The nerve was then stimulated at 

 intervals of about two minutes, central to the area over which 

 nicotin had been painted. Such stimulation always produced a 

 normal effect. However, on painting, the superior cervical 

 ganglion with a similar solution, stimulation of the cervical 

 sympathetic had no effect, while stimulati®n of the nerve fila- 

 ments above the ganglion produced a normal effect. They con- 

 clude therefore that "Nicotin paralyzes the cells of the super- 

 ior cervical ganglion," and further that " the dilator fibers for 

 the pupil, the vaso-constrictor fibers for the ear (probably also 

 those for the head generally) and the secretory fibers for the 

 glands end in cells of the superior cervical ganglion."^ 



As a result of these and other observations with nicotin 

 the following conclusion is reached by them, — " That by stim- 

 .ulating a nerve fiber running to and those running from any 

 peripheral ganglion, before and after the application of nicotin 

 to it, the class of nerve fibers which end in the nerve cells of 

 the ganglion can be distinguished from those which run 

 through the ganglion without being connected with the nerve 

 cells." 



Langley, Anderson and Dickinson and Sherrington have 

 shown, in a series of important contributions, which have ap- 



