770 DR ALEXANDER BRUCE AND DR JAMES W. DAWSON ON 
slight in comparison with the corresponding involvement of the 5th nerve as already _ 
described. Several smaller and superficial patches are situated towards the inner part 
Tic. E. 
of the crus, while a single isolated one, also small in size, is to be seen at a little depth 
from the surface, and probably implicating pyramidal fibres. 
(1) Isonatep NucLeatTep PatcuEs. 
It is necessary again to emphasise that it is such patches which show a break in the 
continuity of the myelin-staining fibres. They are of two kinds: (a) Those of the first 
are small in size, isolated, few in number, and are in no way related to the paths of 
cranial nerves within the medulla or pons; (b) Those of the second are more numerous, 
often extensive, and definitely on the paths of nerves from or to their superficial and 
deep origin. 
(a) In the smallest patches we note that two or three normally-staining longitudinal 
strands, composed of a very few fibres, e.g. in the transverse fibres of the mesial fillet, are 
interrupted in their course by nucleated fibres which seem to be continuous with them. 
The nuclei in these fibres are elongated, with their longitudinal axis parallel to the long axis 
of the tube; they stain darkly, have no nucleoli, and are definitely within the lumen of the 
tube. The transversely-cut strands, between and immediately in relation to the nucleated 
fibres, are also nucleated, so that under low power we have the picture of the normal 
transverse and longitudinal strands of fibres for a short part of their course showing nuclei. 
Under a higher magnification it is recognised that a distinct break occurs on either side — 
of the nucleated fibres, between them and the normal fibres, and that in this short 
interval only glia fibrils are present. These can be definitely followed right through 
the patch, retaining and probably maintaining the longitudinal direction of the fibres. 
A careful analysis of sections stained with Van Gieson’s, iron-heematoxylin, and Biel- 
schowsky’s methods, when this last method has not stained electively and glia fibrils - 
