THE INJURY CURRENT OF NERVE 347 
within their pores solutions in which they are immersed, so that the pores finally 
contain solutions much more concentrated than the 'mother' solution surrounding the 
fibrillar structure. Such a fact is extremely suggestive when the extremely fine 
nature of the interspaces which lie between the fibrillae of the axis cylinder is con- 
sidered. It is more suggestive still when the possibility ot regarding the fibrillae as 
themselves tubular is taken into account. 
Accepting all that is taken as known of the minute microscopical structure ot 
the axis cylinder of the nerve : then there is no inherent improbability in the sup- 
position that the inorganic salts of the nerve might there be held enchained in a 
highly concentrated solution free to move parallel to, but not at right angles to and 
away from the fibrillae. 
Granting such a possibility, we are, however, faced by the important corollary 
that such concentrations are indeed enchained there, and are, therefore, unable to 
exert an osmotic pressure, or by diffusing away give rise to electrical phenomena. 
To explain, in the presence of such an hypothesis, diffusion processes consequent 
upon injury, it seems necessary to invent a phenomenon really secondary to the=injury, 
involving new conditions of the fibrillar structure. 
To invent such a phenomenon is as culpable as the invention of a chemical 
change, and the necessity for doing so is equivalent to the necessity for abandoning 
this supposition. 
On no lines known, therefore, can we explain how we could place and retain in, 
and subsequently allow to diffuse away from the axis cylinders, a highly concentrated 
solution of electrolytes. But the physical capabilities of such a position, in the longi- 
tudinal pores of capillary tubules so minute, are unknown, and beyond the reach of 
investigation. 
Granted strong presumptive evidence of the presence of a highly concentrated 
solution, and of the possibility of its diffusing away from it subsequently to an 
'injury,' it is essential first to criticize severely the nature of the evidence. 
Granted that the evidence is found satisfactory, then the question of possibilities 
may be with greater advantage discussed ; since such a case might in itself light up 
possibilities. 
The experimental work of this research was carried out with the assistance of 
grants from the British Medical Association Scientific Grants' Committee. 
