26 Proceedings of Royal Society of Edinburgh. [sess. 
columns of the spinal cord, and by Wernicke as a downward 
continuation of the posterior commissure. This strand (Plate I. 
fig. 1, Bt.) f which he calls the “centrale Haubenbahn,” appears on 
the posterior and external aspect of the olive. It gradually increases 
in size from the middle of the olive upwards. At the lower part 
of the pons (Plate II. Bt.) it lies between the superior olive and 
the fillet and dorsal to the fibres of the corpus trapezoideum. In the 
upper part of the pons it lies in the middle of the formatio reticularis. 
At the level of the anterior corpora quadrigemina it lies immediately 
external to the posterior longitudinal fasciculus. It then passes 
behind the red nucleus, and enters the lenticular-nucleus loop, to 
terminate, according to Flechsig, in the lenticular nucleus. 
About nine months ago, while making oblique sections of the 
medulla and cerebellum of a nine months’ embryo, in order to 
demonstrate the course of the restiform body (the posterior aspect 
of the section being thus at a higher level than the anterior), I found 
another tract (Plate I. fig. 2, a.o.t .), apparently previously unde- 
scribed. (It is possible that this tract is referred to by Bechterew 
in the paper quoted above.) The strand, which is only indistinctly 
seen in the ordinary vertical transverse sections, begins, like Bech- 
terew’s tract, on the external aspect of the olive. It then bends 
gradually inwards, backwards, and in an upward direction, forming 
a compact bundle, till it reaches the inner side of the nucleus of the 
vii or facial nerve (vii nucl.). Then it turns outwards and slightly 
backwards, crossing the roots of the facial nerve (vii rad.). As it 
does so the fibres spread out from each other in a fan-shaped 
manner, and become less easy to trace. They apparently, however, 
bend somewhat downwards and enter the external (Deiters’ nucleus) 
of the vestibular root of the auditory nerve. 
This connection of the olive with the auditory nerve may serve 
to throw some light on the special function assigned to the inferior 
olivary body in maintaining the equilibrium of the body. 
Explanation of Plates. 
Plate I. fig. 1. — a.p., anterior pyramid; i.o., inferior olive; B.t., Bech- 
terew’s tract ; V.Asc., ascending root of fifth nerve ; c.r., corpus restiforme. 
Plate I. fig. 2. — a.p., anterior pyramid; inf. olive, inferior olivary body; 
v.Asc., ascending root of fifth nerve ; vii nucl., nucleus of facial nerve; vii 
