1 8 Journal of Comparative Neurology. 



only in a small percent, did I obtain results which might be 

 looked upon as satisfactory, and by this is meant that only in a 

 few experiments were the nerves on the larger as well as the 

 smaller vessels, and in different regions of the pia-mater well 

 stained. In a much larger number of experiments they were 

 well stained in certain regions, sometimes on one side and not 

 on the other, again on one portion of the circle of Willis and not 

 on the remaining portion, sometimes medullated. sensory fibers 

 and not vaso-motor or vice versa, etc. ; although after some pre- 

 liminary experimentation, the same method — strength of solu- 

 tion, quantity, time of exposure, etc. — was used in all the expe- 

 riments. 



It seemed therefore ill-advised to continue this line of 

 experimentation. Before leaving, however, these experiments, 

 attention may be drawn to the fact that after the extirpation of the 

 ganglia as above described, in nearly every experiment certain 

 vessels of the pia stained a peculiar, greenish blue color, quite 

 unlike the deep blue color seen after the injection of methylen 

 blue into normal vessels, It is to be born in mind that the 

 muscle cells of the vessels show a selective action toward the 

 methylen blue. I am not prepared to say that this change in 

 the reaction of the muscle cells toward the methylen blue, after 

 the extirpation of the sympathetic ganglia of the neck, indicates 

 a chemical change in the protoplasm of these muscle cells, per- 

 haps as a result of trophic influences interrupted at the removal 

 of the cell bodies of sympathetic neurons, sending neuraxes to 

 these vessels. I offer this as a possible explanation of a 

 phenomenon observed in many of the experiments here under 

 discussion. 



In the preceding pages I have drawn attention to the 

 nerves in the pia-mater of the cerebral hemispheres, and more 

 particularly to the nerves, — sensory and vasomotor, — found in 

 conjunction with the middle cerebral and its branches. I can 

 not state positively that I have been able to trace any such 

 nerves into the substance of the brain. In preparations of the 

 pia, prepared after the method described (namely, removing 

 the pia-mater with a portion of the brain cortex to a slide and 



