MULTIPLE NEUROMATA OF THE CENTRAL NERVOUS SYSTEM. 785 
Obviously, then, to go further in our conclusions than our actual observations 
justify, we need to start with a good deal assumed. The one conclusion that appeared 
as a natural consequence of our observations—the multicellular structure of the fibres 
composing the nodules—leaves much still to be explained, and for this further explana- 
tion we must have recourse to deductions from conclusions accepted by other workers. 
Nature of the Cells.—The development of the cells thus enclosed in the brain and 
spinal cord into nucleated tubes and fibres suggests that they were destined to form 
such structures in the ordinary course of development. For collateral evidence on this 
point we refer again to the development of nerve fibres in the embryo and in tumour 
formation. 
(a) In embryonal development.—Numerous observations point to the possibility 
that the cells of the early medullary tube differentiate along three lines to form 
ganglion cells, glia cells, and nerve fibre cells—-cells which migrate and form cell-chains 
and are therefore peripheral neuroblasts. Other observations point to the possibility 
that the indifferent cells of the spinal ganglionic anlage ditferentiate into ganglion cells, 
capsule cells, and nerve fibre cells. In each case the nerve fibres are only secondarily 
brought into connection with the process of the ganglion cell. The prototype of the 
ganglion cell (central neuroblast), glia cell, and nerve fibre cell (peripheral neuroblast), 
is the same mother-cell. Similarly, in the sympathetic ganglionic anlage, indifferent 
cells differentiate into ganglion cells, nerve fibre cells, and chromotrope cells. 
(6) In tumour formation.—In the ganglio-neuroma, described by Faux and 
Verocay, the origin of the ganglion cells and nerve fibres has been traced to a common 
parent cell—the early indifferent cell, which has remained undeveloped. The nerve 
fibres found in these tumours in varying stages of development are ascribed to these 
cells as nerve builders and not to the ganglion cells, which were too immature—in 
many cases quite a-polar—to have formed them. The importance of Koun’s re- 
searches on the development of the sympathetic is of special significance in relation 
to the development of ganglio-neuroma. These tumours are traced to indifferent cells 
which have not achieved their differentiation and evolution, and, later, fulfil their 
destiny in an exaggerated degree. The presence of ganglion cells, nerve fibre cells, 
and chromotrope cells has been described by numerous writers in such tumours, 
especially those developing in relation to the medulla of the adrenal. 
In some of the tumours of the cranial nerves described by Verocay, and in the 
tumours of the Gasserian ganglion and intra-cranial portions of the cranial nerves, 
described by Rise, ganglion cells, glia cells, and nerve fibre cells could be traced in 
all stages of transition between a common undifferentiated type to mature ganglion 
and glia cells and nerve fibres in different stages of development. Such observations 
are obviously dificult of objective proof, but their importance lies in the conception of 
the authors that the tumour formations must be traced to an undifferentiated cell 
which realised to differing degrees the differentiating possibilities present in it in the 
form of all three components of the nerve tissue. VERocay has suggested the term 
TRANS. ROY. SOC. EDIN., VOL. XLVIII. PART III. (NO. 27). 112 
