24 Journal of Comparative Neurology. 



turally — resemble vaso-motor nerves found in other organs, 

 have in a number of instances been found in the pial vessels, 

 suggests at least the advisability of a renewed investigation of 

 this problem at the hands of the physiologist, if indeed, con- 

 sidering the complexity of the problem, the question may be 

 decided from this standpoint. I am reminded here of a similar 

 doubt expressed by Obersteiner (2) in the article from which I 

 have already quoted freely. After stating, and agreeing in this 

 respect with Mosso, that the vessel-nerves of the brain are 

 easily fatigued and fail to respond at a time when vaso-motor 

 nerves still react in other organs, he adds: " Diese besondere 

 Ermiidbarkeit konnte vielleicht auch zur Erklarung der nega- 

 tiven Versuchresultate mancher Forscher herangezogen werden. 

 Jedenfalls gestatten alle derartigen experimentellen Ergebnisse 

 mancherlei Auslegung und sind nicht geeignet eine entschie- 

 dene Beantwortung der Frage nach dem Vorhandensein von 

 Nerven an den Gehirngefassen zu ermoglichen. " 



REFRENCES TO LITERATURE CONSULTED. 



1. Lovell Gulland: On intracranial pressure and the cerebral circulation. Part 



IL Histological. Journal of Physiology. Vol. XVIII, 1895. 

 Page 361. 



2. Obersteiner: Die Innervation der Gehirngefasse. Arbeiten aus dem Insti- 



tut fiir Anatomie und Physiologic des Centralnervensystems an der 

 Wiener Universitat. V, Heft, 1897. Page 215. 



3. Lovell Gulland: The occurrence of nerves on intracranial blood vessels. 



British Medical Journal, Sept. 17, 1897. P^g^ 78- 



4. Quain's Anatomy. Vol. III. Pt. II. Pages 362 and 366. 



5. Testus: Traite d'anatomie humaine. Tome II. Page 665. 



6. Kolliker: Handbuch der Gewebelehre des Menschen. Vol. II. Page 835. 



7. Bourgery and Arnold : Obersteiner loc. cit. 



8. Tuckett: On the structure and degeneration of non-medullated nerve fibers. 



Journal of Physiology. Vol. XIX. Page 267. 



9. Alexander: Bermerkungen iiber die Nerven der dura Mater. Archiv fiir 



Mikroscopische Anatomie. Vol. XI, 1875. Page 231. 

 10. Leonard Hill: The physiology and pathology of the cerebral circulation. 

 London, 1S96. References to other papers mentioned may be 

 Tound in this volume on pages 202-204. 



