1905. | The Structure and Function of Nerve Fibres. 337 
rather regard them as polarised regions of the fibre involved secondarily in 
the transmission of the injury-current. In this connection I might put 
forward the claim that the observation of an axis-cylinder carrying this wyury- 
current provided the very best means for exanvining the state of a colloidal 
solution traversed by absolutely parallel stream-lines of current. 
In direct support of the possible existence of such a condition of “ pseudo- 
polarisation,” I might also mention the “true longitudinal polarisation” ot 
nerve. Place a piece of nerve as truly in a straight line as possible between 
non-polarisable electrodes, and pass a current through it, then, on removal of 
this current, a “ polarisation” (?) current is observed to traverse it in the 
reverse direction. This phenomenon has attracted some attention, since the 
whole of the polarisation phenomena of nerve have been attributed to 
the passage of the current through the walls surrounding the axis-cylinders, 
and in this case it is not obvious that any such traverse has taken place. 
It is true that an explanation has been found for it in the assumption that 
the fibres have not been placed in true rectilinear fashion between the 
electrodes. To me, however, this explanation has never appealed, possessing 
considerable faith in the relatively greater magnitude of the conductivity of 
the axis-cylinder, and not aware that slight twists in the direction of an 
insulated wire produced much leakage of the current through the insulation. 
I have also, however, observed the phenomenon under conditions in which 
such twisting could not. be supposed to have occurred to any degree worth 
inentioning, as, for example, when thin slices of a ‘stout nerve-trunk were 
placed in this manner between the electrodes. 
Imbued with the idea that “ membranes” formed a necessary factor in the 
production of all the internal polarisation phenomena occurring in living 
tissues, I was at the time inclined to’ postulate the existence of theoretical 
membranes arranged transversely to the longitudinal axis of the nerve-fibre, 
perhaps at the nodes of Ranvier. During the present investigation, however, 
I have frequently watched the granular conditions I have described pass 
uninterruptedly through the nodes, and have thus become convinced of the 
uninterrupted continuity of the axis-cylinder, and, therefore, of the absence 
of transverse membranes from these nodal points. This newly-described 
condition of “ pseudo-polarisation,” however, provides a complete explanation 
of the phenomenon of true longitudinal polarisation, just as it at the same 
time provides an explanation of the manner in which the electrolytes of the 
nerve may be set in motion in measurements of electrical conductivity, 
although usually locked up in its normal state of colloid solution. 
The condition of “pseudo-polarisation,” therefore, has certain’ direct 
evidence in support of its existence, and, further than that, its existence 
