HuBER, Innervation of the Inttacranial Vessels. 1 5 



cular plexuses here discussed terminate in the muscular coat of 

 the pial vessels, one may often observe in well-stained methylen 

 blue preparations mounted in ammonium picrate-glycerine. In 

 such preparations, by careful focusing, very delicate varicose 

 threads are now and then found in the muscular coat, running 

 parallel to the long axis of the involuntary muscle cells. To 

 make certain, however, the serial sections, to which reference 

 has previously been made, were studied with special reference 

 to this point. In such sections — double-stained in methylen 

 blue and alum carmine — very delicate varicose fibrils, stained 

 blue, are found between the non-striated muscle cells of the ves- 

 sel wall, which are stained red. And here and there in fortu- 

 nate sections, these were seen to give off short lateral twigs ter- 

 minating in fine granules on the muscle cells; in other words, 

 the ultimate ending of the nerves in involuntary muscle tissue. 

 To one familiar with the appearance of methylen blue prepara- 

 tions, fixed, hardened, sectioned and counterstained as above de- 

 scribed, blue granules or even short blue fibrils do not of neces- 

 sity indicate the presence of a nerve ending ; for, unfortunately, 

 tissues other than nervous stain blue and blue granules which 

 appear to be nothing but precipitate are often seen. This I 

 have tried to bear in mind, and only such granules or small end- 

 discs, were accepted as the ultimate ending of perivascular 

 nerves in the muscular coat of the pial vessels, when I was able 

 to trace a connection between them and a blue fibril which from 

 its varicosity, color reaction and other appearances I was led to 

 regard as a nerve fibril. The arrangement and mode of ending 

 of the perivascular nerves in the pia-mater being in every respect 

 like that of vaso-motor nerves in other parts of the body, I feel 

 warranted in placing them in the same category. 



Assuming that the non-medullated nerve fibers of the peri- 

 vascular plexus found on the carotid artery were the neuraxes of 

 sympathetic neurons, the cell bodies of which were situated in 

 the superior cervical ganglion, and that those found on the verte- 

 bral arteries were the neuraxes of neurons, the cell bodies of which 

 were to be found in the inferior cervical and stellate ganglia, 

 I extirpated these ganglia in pairs, with the hope that the 



