THE NERVUS TERMINALIS IN THE ADULT DOG 



AND CAT 



ROLLO E. McCOTTER 



The Analoniicid Ldljorntory, University nf M Ichigdii, Ann Arbor 



FOUR FIGURES 



In a previous communication the writer ('12) has shown the 

 presence in mammals of tw^o distinct groups of nerve fibers in 

 the olfactory region which terminate in separate ganglionic masses 

 on the surface of the olfactory bulb. These are the common 

 olfactory fibers arising from the olfactory mucosa, and the vomero- 

 nasal nerves arising in the vomeronasal organ ( Jacobson's organ) . 

 The former ramify in the glomeruli of the olfactory formation 

 and the latter terminate in similar structures in the accessory 

 olfactory bulb, or, as we might better designate it, the vomero- 

 nasal formation. In the same paper it was suggested that we 

 might have to add to these a third group, the nervus terminalis 

 which apparently differs essentially from the previous two groups. 

 It was also mentioned that, judging from the dissections of 

 adult dogs, it might be possible to demonstrate all three of these 

 nerve groups in that animal. Since that time, as will be reported 

 in the present paper, the writer has succeeded in clearly demon- 

 strating in both the adult dog and cat the existence of a slender 

 ganglionated nerve which in its position and character corre- 

 sponds completely with the nervus terminalis as described by 

 previous authors in lower forms. In other mammals it is either 

 extremely small or is absent. The writer made a careful search 

 for it in the opossum, rat, rabbit, guinea-jDig and sheep and did 

 not succeed in finding it. 



Before describing the details of the connections of these nerves 

 it may be well to remind the reader that the nervus terminalis 

 was first described in 1894 by Pinkus who found it in ProtojD- 



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