766 DR ALEXANDER BRUCE AND DR JAMES W. DAWSON ON 
from that in the spinal cord. The finding, however, of one or two nodules with 
definite whorl disposition of the fibres, presenting, as it were, a transition to the more 
fully developed nodules in the cord, led to the possibility being entertained that these 
formations were early stages in the development of one process. Later findings also 
emphasised the nervous nature of the constituent elements of the early nodules. 
The examination under low power of Weigert-fuchsin and iron-hematoxylin- 
fuchsin preparations at different levels of the medulla and pons showed that the fibre- 
_ tracts were here and there interrupted and replaced by small patches which took 
a diffuse faint connective-tissue stain to a greater or less extent; in these areas, under 
a higher magnification, faint lines could be recognised taking the myelin stain. In 
similar sections stained with the Bielschowsky - Williamson silver method, the 
fibres were again interrupted by faintly-staining areas in which were found diffusely- 
staining fragments of axis-cylinders, and in adjoining sections stained with Van 
Gieson’s method it was demonstrated that these areas which had stood out so clearly 
under a low power as patches of degeneration were in reality patches of nucleated 
fibres and nucleated elements cut transversely, obliquely, or longitudinally. ‘The 
fibres, in many instances, seemed to retain the normal arrangement of the fibre strands 
of the part involved (figs. 57 and 58). In other parts the fibres terminated in a 
loose meshwork of interlacing, nucleated fibres, or strands of such nucleated fibres 
ended in a vortex of elongated nucleated elements which diverged from each other 
to interlace with similar elements from adjoining strands (figs. 59-62), Such areas 
showing this loose structure were in all instances closely related to the tissue around 
hlood-vessels. The iron-hematoxylin stain very readily revealed the existence of 
even the smallest nucleated patches, as it showed the break in the continuity of the 
normal fibres, and, further, the minute nuclear structure of the elements replacing 
them could be ascertained in one and the same section. 
In the pia a few fully-stained medullated fibres around vessels were found, but 
in no case did these form strands or nodules in the vessels or pial spaces. OBERSTEINER 
has observed that the cranial pial vessels usually contain such fibres, while the spinal 
pial vessels rarely do so. 
From this brief description it is seen that there are present in the medulla and 
pons abnormal formations which bear a certain structural resemblance to one another. 
For purposes of description we distinguish between the following :— 
(1) The simplest nucleated patches with the retention of the normal framework 
of the tissue ; 
(2) The patches in relation to sensory nerve paths ; 
(3) The patches which consist of a loose meshwork of interlacing nucleated fibres 
and spindle-shaped elements; 
(4) The definite nodule formation ; 
(5) The areas in relation to the superficial origin of motor nerve roots ; 
(6) The areas of pure fibrosis, 
