176 On the Active Part of the Nerve Fibre, 
not be able with certainty to distinguish one from the other. Can 
the axis cylinder be regarded as anything more than a very elongated 
band composed of a texture closely allied to white fibrous tissue, 
hut formed of perfectly parallel and continuous strata, not disposed 
as distinct fibres, but nevertheless tearing in the longitudinal 
direction ? In many instances, however, the axis cylinder exhibits 
a tendency to break transversely, and in several of my specimens I 
have seen oblique lines, but whether these should be regarded as 
natural I am not sure. In one preparation which has been kept 
for some time the nerve (axis cyhnder) near an oval nerve cell 
exhibits a distinctly spiral or corkscrew-like arrangement, as if it 
had been twisted round and round in the same direction during its 
formation. At the same time I have never been able to demonstrate 
any remarkable peculiarities of structure in the axis cylinder. 
Even under the highest powers only a fibrous appearance can be 
discerned. Anatomical observation almost justifies the idea that if 
it were possible to replace an axis cylinder by a long filament of 
ordinary fibrous tissue, we should find that this would conduct the 
nerve current as effectually as the ordinary axis cylinder itself does. 
To me it appears very doubtful if the axis cylinder is capable of 
undergoing any remarkable change in ultimate arrangement during 
nerve action, and I think that whatever change does take place it 
is of such a nature that it might occur in other forms of tissue. 
The peculiarity of the nervous system upon which all its charac- 
teristic phenomena depend is probably not any remarkable arrange- 
ment of its ultimate molecular structure, but simply uninterrupted 
continuity of conducting tissue. Nor have we reason to think 
that the bioplasm which forms nerve tissue grows or lives very 
differently from other forms of bioplasm. It receives its nutrient 
material from the same blood and is derived from the same masses 
which give origin to other forms. Considering the characters and 
arrangement of the bioplasm matter and its relation to the formed 
material in all tissues, it is not unreasonable to conclude that 
currents, and perhaps of the same nature as those discharged by 
nerve organs, are set free, but that it is only in the case of nerve 
that an arrangement exists suitable for insulating the currents and 
for rendering evident, variations in their intensity, rate of trans- 
mission, &c. 
The general arrangement of the fibres and cells in all central 
and peripheral nerve organs ; the structure and arrangement with 
respect to one another of all nerve fibres which pass through a con- 
siderable distance before they reach their destination ; the manner 
in which nerves act upon contractile tissues, and the circumstance 
that a current of electricity produces a similar action ; and the fact 
that electricity is set free in special organs which are very rich in 
nerves, but which do not differ in any essential particulars in ulti- 
