ME. J. L. CLARKE ON THE INTIMATE STRUCTURE OF THE BRAIN. 307 
(66) Fig. C represents the next deeper, but similar kind of, section. The pigmentary 
matter at the inner side of the grey tubercle, as well as the oblique 
fibres, have disappeared ; but other fibres issuing from the base of the 
grey tubercle (a 1 ) ascend and curve inward to the nucleus of the third 
nerve {/)■ Adjoining these on their inner side, and ascending to the 
same place, are the white fibres (ii), which have passed through and 
beneath the common nucleus of the facial and abducens nerves, as well 
as those fibres which run along the side of the median furrow. Hence 
it appears that hotli the base of the grey tubercle into which the 
sensory root of the trigeminus penetrates , and the bundles of fibres 
which pass through and beneath the common nucleus (Q"), are con- 
nected with the nucleus of the third nerve. 
Of the Trapezium and Superior Olivary Bodies. 
(67) In the Proceedings of the Royal Society for June 1857, I first showed that the 
transverse band of fibres known in animals as the trapezium encloses on each side a 
remarkable grey nucleus which bears a striking resemblance to the olivary body ; and 
I further showed, at the same time, that the trapezium with its nucleus exists also in 
Man, but that it is covered and concealed by transverse fibres at the lower border of 
the pons. About a year later the grey nuclei of the trapezium, in animals , were 
described by Schroder van der Kolk, and called by him the superior olivary bodies*. 
As the structure of these nuclei has since been more fully investigated by Dean f , it 
will be unnecessary to go over the same ground; and therefore I shall only point out 
the chief differences in structure and position between the trapezium of Man and that 
of animals generally. 
(68) On turning to fig. 48, Plate XII., which represents a transverse section of 
the left lateral half of the medulla of the Rabbit on a level with the auditory nerve, a 
remarkable group or column of large cells (s) will be found imbedded in the anterior 
part of the antero-lateral column, on the outer side of the anterior pyramid. This group 
of cells was first pointed out by myself J, and was subsequently named by Dean the 
antero-lateral nucleus. It begins low down in the medulla, both in Man and animals, 
and ascends as high as the trapezium §. Here, however, we find it replaced, exactly in 
the same spot, by another nucleus of a different form and somewhat different structure. 
This consists of a convoluted grey lamina like that of the olivary body, but the convolu- 
tions are few. In the Rabbit ( s fig. 61, Plate XIY.) and in the Cat, in which it is 
largely developed, it assumes rather a sigmoid form, with some small masses on its inner 
side. In the Sheep and other Ruminantia there is less trace of convolutions. The cells 
of the lamina are smaller than those of the antero-lateral nucleus, and the course of its 
* Schroder tar der Kolk, Medulla Oblongata, 1858. 
t Medulla Oblongata and Trapezium. By John Dean, M.D. 
+ Philosophical Transactions, 1858. § Ibid. 
Fig. C. 
