THE VIBRISSA OF CERTAIN MAMMALS.^ 

 By J. Franklin Messenger, M.A. 



Studies from the Hadley Laboratory of the University of New Mexico. 



Communicated bv C. L. Herrick. 



With Plates XXVII to XXIX. 



The lower mammals, in contrast to man, are endowed with 

 a peculiar class of sensory organs developed upon certain mod- 

 ified hairs, the vibrissse. While these share with the ordinary 

 hairs a tactile function, they differ from the hairs of the general 

 surface not merely by having this common function intensified; 

 but there is a fundamental difference in the way in which the 

 accommodation to that function is accomplished. 



President C. L. Herrick has suggested in various papers 

 an intimate relation between vascular changes and the emotional 

 element or tone in sensation and that vascular change may ex- 

 plain periods of latency in the development of pain concomi- 

 tants of sensation. It was at his suggestion and with a view 

 to the determining whether there was any connection between 

 the vascular mechanism and sensory apparatus of the vibrissa 

 that these studies were undertaken. 



Present opportunities prevent any complete canvass of the 

 literature, so that the facts are presented as briefly as possible as 

 a commentary on the plates, which will illustrate the relations 

 in the two types studied. 



The tissues were from the muzzle and feet of young dogs 

 and rabbits and were subjected to a variety of treatment in 

 hardening and staining. For our purpose we soon Hmited the 

 experiment to the rapid Golgi process, iron haematoxylin and 

 combined hsernatoxylin and picro-carmine. Of these the Golgi, 



* In partial satisfaction of thesis requirements for the degree of Master of 

 Arts in the University of New Mexico. 



