780 DR ALEXANDER BRUCE AND DR JAMES W. DAWSON ON 
III.—INTERPRETATION AND CONCLUSION. 
In trying to answer the question, What conclusions may be drawn from our obser- 
vations ? or, in other words, What is their explanation? we are met at the outset by the 
necessity of bringing, if possible, the various formations described into a genetic relation 
to one another. In the attempt to correlate the appearances in the cord with those in 
the medulla oblongata and pons the problem in the cord is, obviously, the genesis of 
the nerve fibres, for these elements are the essential constituent of the nodules, while 
the problem in the medulla and pons is the genesis of the fusiform cells, for the various 
formations can be related to them. 
In the cord the fibres were disposed, more or less, in the form of strands or nodules 
in numerous positions. They were found always in relation to pia, pial septa, or the 
adventitia of vessels, and only in their terminal ramifications did the individual fibres 
come into direct contact with the actual nerve tissue. The fibres of the nodules could 
in all instances be traced to strands passing laterally or ventrally from the immediate 
vicinity of the emerging anterior roots. Those passing laterally in the pia entered 
inwards by all the peripheral vessels of the lateral region of the cord ; they formed 
nodules in the vessel-walls and at the junction of white and grey matter, where their 
fibres terminated by gradually unweaving themselves from the nodule into the general 
texture of the grey matter. The fibres passing ventrally curved round into the anterior 
fissure, as a rule to its base, forming a large nodule in the region of the central canal, 
passed along the commissural vessels to form nodules in the centre of each grey matter, 
and often leashes of fibres passed along in the vessel-walls anteriorly, laterally, and 
posteriorly. The terminal fibres of these nodules again gradually unwound into the 
general meshwork of the grey matter, interlacing with fibres from the nodules which 
had formed in relation to peripheral vessels. 
With Weigert’s medullated sheath stain these fibres are found to have a specifically 
but faintly-staiing myelin sheath with short and bulging interannular segments ; with 
Cajal’s silver method for medullated nerves the axis-cylinder stained specifically ; and 
with nuclear stains the fibres gave the appearance of peripheral nerves with, however, a 
finer general structure, and more numerous and larger nuclei. The nuclear stains 
revealed also—what the myelin sheath and axis-cylinder stains had only slightly indi- 
cated—that the fibres in their terminal ramifications were continuous with nucleated 
protoplasmic tubes in which a central filament and a homogeneous outer zone could be 
recognised, corresponding to the axis-cylinder and myelin sheath, and, further, that 
these nucleated tubes could be traced frequently to terminate in fusiform, nucleated 
elements. Some of these were simply the sections of the nucleated tubes cut in various 
directions, but others could be satisfactorily and definitely proved to be individualised 
fusiform cells. In some of these cells could be traced a fine continuous deeply-staining 
filament in the protoplasm on one side of the nucleus. 7 
