The Nervus Terminalis I N the Adult Dog and Cat

I n a previous communication the writer (’12) has shown the presence in mammals of two 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 vomeronasal 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 vonieronasal 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 niight 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 demonstrating in both the adult dog and cat the existence of a slender ganglionated nerve which in its position and character corresponds 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-pig 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 Protop-