MULTIPLE NEUROMATA OF THE CENTRAL NERVOUS SYSTEM. (eit 
up into these fusiform cells, are the growing points of the fibres, and that the most 
fully evolved and differentiated part is the oldest part of the fibres. In the cord this 
part of the fibres is in the pia, in the immediate vicinity of the anterior roots; in the 
medulla and pons the most fully-ditferentiated fibres are in the more central parts 
of the nodule, and the winding of the fibres, as it were, has taken place around the 
first-formed elements. The fibres in these positions are derived, therefore, from 
“rests” of undifferentiated cells of the value of peripheral neuroblasts, which have 
been carried in to the tissue m the walls of the ingrowing vessels, and which go on to 
the production of a neurogenous tissue which reaches the stage of embryonic fibres— 
the protoplasmic bands of Durante. The fibres in the cord have arisen from “ rests” 
of undifferentiated cells left in the immediate vicinity of the part where in normal 
development the fibres are first laid down. As the spaces in the pia and pial septa 
give them a free path of growth, they develop in parallel and intertwining strands, and 
only later, when possibly they méet with some difficulty in their path, do they assume 
a twisted and nodular form. ‘The precise origin of the fibres from the point immedi- 
ately peripheral to the Ablassungzone of the anterior nerve roots is explained by 
the fact that here probably the nerve fibre cells, according to this view of their 
development, are first likely to be deposited. 
Still assuming the peripherist view of the origin of the nerve fibre from a cell- 
chain, the question arises: Is it possible for such indifferent cells of the value of 
peripheral neuroblasts, independent of any central influence and function, to differ- 
entiate to the stage of the most fully evolved fibres in the cord? An answer to this 
question would be rendered easier if we could indicate the period at which these 
nodules have arisen. Is it that in a very early stage of development, pari passu with 
the development of the blood-vessels, indifferent cells have laid down embryonic nerve 
fibres? In such a case we find it easy to understand that this abnormal cell-chain 
might become linked on to the process of a cenvral neuroblast just as the normal 
anterior roots become connected. If these, then, were such aberrant nerve roots, the in- 
completeness of their differentiation would be sufficiently accounted for by the sterility 
of their function. In such a case, however, we would have to admit that nodules with 
fibres having no function have persisted through life in spite of the supposed inherent 
weak vitality of such fibres. On the other hand, is it possible that undifferentiated 
potential peripheral neuroblasts have remained undeveloped at the point of their first 
deposition, and in later life have taken on a proliferative activity which has resulted 
in the formation of nerve fibres? The most fully evolved portions of such fibres have 
remained as parallel strands near the point of their formation, because the free lymph 
space in the pia and pial vessels has allowed the progression, laterally and ventrally, 
of the fibres. 
Returning now to our question regarding the stage to which peripheral neuro- 
blasts alone may achieve the differentiation of the nerve fibre, we must refer to 
evidence obtained from the regeneration of nerves and from tumour formation. 
