THOMPSON YATES LABORATORIES REPORT 
deeply-situated nerve fibres, was elaborately investigated by Du Bois Reymond. 1 
His inferences strengthened by the mathematical work and physical experiments of 
Helmholtz 2 explained the complex distribution of potential differences upon the 
nerve trunk surface, as due to a simple distribution of oppositely electrically charged 
surfaces upon the individual nerve fibres. The zinc-copper model exemplifies these 
inferences, and its composition is a standing witness to the fact that the complex 
superficial conditions are, to a great extent, the outcome of an examination of the 
nerve trunk when longitudinally isolated from the surrounding structures, and exam- 
ined in air. The complex condition then found upon the surface of the nerve trunk 
is new, is not the same as the conditions existent upon its surface when clothed in 
the neighbouring tissues, nor is it the same as the conditions existent upon the im- 
portant elements of its structure. 
In concentrating attention upon the individual nerve fibre and its physical 
structure, and after a laborious investigation of surface distribution, legitimately 
delving from this the essential nature of the problem as it affected the individual nerve 
fibre, Du Bois Reymond may be said to have not only discovered the ' apparent ' but 
also the ' real ' phenomenon. The whole longitudinal surface of the individual nerve 
fibre is probably equally positive, the whole transverse surface uniformly negative. 
The gradual transition, which apparently takes place in the surface conditions as we 
pass from the cross section in towards the unbroken nerve fibre, has probably no 
parallel in a varying state of the nerve fibre. The nerve fibre at its cut end is 
negative. The longitudinal surface in the neighbourhood of this cut end appears 
less positive than the remainder of the longitudinal surface, simply because of its 
physical juxtaposition to this negative surface. 
Section 1 
■ 
Explanatory Theories. Du Bois Reymond 
Of these facts and legitimate inferences, various explanations have been offered. 
Du Bois Reymond based his explanation entirely upon the constitution of one 
primarily important structural element of the nerve fibre. He used, in fact, the data 
obtained from observations upon the manner of origination and conduction of 
electrical currents by the nerve as a base from which to obtain knowledge of the 
main physical characteristics of the structure of the nerve fibre. It is a matter for 
regret that he did not sufficiently recognize in the nerve fibre the existence of not 
one but several structures of possible importance. It is true that before committing 
himself finally to such a position he was careful to examine the other two lines upon 
I. Du Bois Reymond, Vntermchungen. Bd. I, p. 672. 1849. The original work was done upon muscle 
but confirmed for nerve. 
z. Helmholtz, Pogg. Ann, Bd. LXXXIX, p. 212. 1853. For a full account see also A. Fick, Die Medhinisc/ie Physik, 
Braunschweig, 1858 ; or C. Morgan, Electro-physiology, New York, 1867. 
