OF THE GYRUS MARGINALIS AND GYRUS FORNICATUS IN MONKEYS. 345 
Sinned Cord. Cervical Enlavejement. —There is a well defined patch of degeneration 
involving the whole crossed pyramidal tract on the left side, triangular in shape, with 
the base towards the posterior cornu and the apex at the middle of the lateral surface 
of the cord. The apex spreads out along the circumference posteriorly, and encroaches 
for a short distance upon the cerebellar tract. The degeneration extends far forwards, 
as in most of the other similar lesions; the mesial part of the degeneration (the part 
towards the grey matter) is less concentrated than the part bordering the direct 
cerebellar tract. There is a little sclerosis. 
On the right side (side of the lesion) there is a small amount of degeneration and 
sclerosis, scattered over a similar area. 
Dor,sal Region (fig. 4c).—The degeneration occupies the whole area of the crossed 
pyramidal tract, and appears even to extend in advance of that tract. 
It is more concentrated than higher up, as is the case in all dorsal sections. In the 
lower dorsal region the degeneration has much the same appearance, except that it is 
altogether nearer the circumference of the cord, and does not extend as far forwards. 
There is a very small amount of degeneration in a similar position on the opposite 
side. 
Lumhar Enlargement. degeneration here is irregularly oblong in shape, and 
extends from the postero-lateral groove along the circumference for about one-fourth 
the distance from that groove to the anterior median fissure. 
It does not touch the posterior cornu, except near the root exit. 
No degeneration can be seen on the right side (side of the lesion). 
Case 11.-— No. 42 of Eirst Series. (Figs. 6a, 66, and 6c.) 
Lesion 1.—Removal of the anterior two-thu’ds of the left gyrus fornicatus (see 
fig. 6a, Plate 27). Frontal sections through the brain show that only that part of 
the gyrus fornicatus which is seen on the mesial aspect was completely removed, 
those portions of the gyrus which lie next the corpus callosum and at the bottom 
of the calloso-marginal fissure having remained practically intact."'" 
Result. —Great diminution of sensibility over the right side of the body, which 
gradually, but Only partially, passed off. Some muscular paresis on the right side, 
especially of the leg. 
Lesion 2.—Eleven weeks after the operation, the right gyrus was exposed and 
injured by scratching with a needle. The permanent injury caused by the needle wa 
so slight as hardly to be perceptible. No result was observed during life. 
The animal was killed thirteen weeks after the first operation. 
* It is especially to be noted that in this case there was no perceptible injury of any region, excitation 
of which has been proved to produce muscular movements. 
MDCCCLXXXIX.—B. 2 Y 
