OF THE GYRUS MARGINALTS AND GYRUS FORNICATUS IN MONKEYS. 333 
universal applicability (to both central and peripheral nervous system) regarding- these 
phenomena, is the Wallerian, that degeneration supervenes in all nerve fibres which 
are cut oflf from their nutrient centres, which in all pi-obability are the cells from 
which the fibres have originally grown out (His). The nutrient centres for the higher 
motor tracts lie in the grey matter of the cerebral cortex, and there is nothing intrin¬ 
sically improbable in the supposition that those for the higher sensory tracts are also 
to be found there. To decide between these two explanations must be the object of 
future investigations. [E. A. Schafer.] 
ON THE DESCENDING DEGENERATIONS WHICH FOLLOW LESIONS OF THE 
GYRUS MARGINALIS AND GYRUS FORNICATUS.* 
Summary of the Degenerations which follow Marginal Lesions. 
I have examined six cases where a lesion in the marginal convolution was produced. 
In two cases this injury was strictly confined to the marginal (cases 1 and 4), the 
gyrus fornicatus being quite uninjured. 
In the remaining cases there was some injury to the adjacent external surface of 
the hemisphere, or to the gyrus fornicatus. 
In the internal capsule the degeneration has been difficult to detect, and all that I 
can say, as far as this series is concerned, is that I have not seen degeneration in front 
of the knee, but have occasionally been able to make out scattered degenerated fibres 
in the posterior half 
In the 'pons the degeneration is easily seen, scattered, apparently indiscriminately, 
in the pyramidal bundles. If the cortical lesion had been extensive and the animal 
had lived for some time (ten weeks or more), a distinct difference in the size of the 
bundles on the two sides could be seen with the naked eye after hardening. 
The medulla ohlongata also shows degeneration in the pyramids. Here it is more 
concentrated than in the pons. A shrinking of the pyramid coiu’espondiiig to the side 
on which the cortical lesion has been made similar to that in the pons can be seen 
with the naked eye if the animal has lived long enough for much sclerosis to have 
been set up (see fig. 2b, Plate 28). 
In the spinal cord the degeneration is continued in the crossed pyramidal tract on 
the side opposite the lesion, and can be traced in this tract as far as the lower lumbar 
region. 
I have not found degeneration in the direct pyramidal tract in any case. In all 
cases where the degeneration in the crossed pyramidal tract on the side opposite the 
lesion is well marked, degeneration in the crossed pyramidal tract on the same side as 
the lesion can also be seen (see fig. 2d), occupying a similar position to that on the 
* Tlie remainder of the paper is by Mr. E. P. France. 
