268 
THOMPSON YATES LABORATORIES REPORT 
The statement made above, though so briefly given, has involved years of con- 
troversy and experiment upon the part of several investigators, notably Hermann and 
Grunhagen. This controversy has been now brought to a clear termination by the 
introduction into the subject of knowledge of the possibilities, within which the 
conduction of electrical currents by moist conductors is limited, by the ' electro- 
chemist ' Nernst. 
The statement of electro-chemistry is definite. Polarization cannot occur between 
two moist conductors (solutions of electrolytes) unless they are separated by a 
physical membrane (pre-existing high resistance). The introduction of the third material 
is, therefore, a necessity, and its nature is even to a certain extent defined, for the term 
' physical membrane ' implies a material which habitually acts as a barrier, limiting 
material particles moving in diffusion processes, and also, as in this case, the particular 
particles ' Ions' which are set in motion during the passage of an electrical current. 
Practical experience is, therefore, amply confirmed by theoretical consideration. 
Definite as is the statement of 'electro-chemistry' as well represented by Nernst, 
it is of interest that a similar statement was also simultaneously made by a physiolo- 
gist making use in other fields of electro-chemical data and methods. This statement 
is, unfortunately, hidden away from the special literature of 'muscle and nerve,' 
inasmuch as it appears in an article on blood and blood corpuscles. It seems there- 
fore pardonable to quote it in some detail. G. N. Stewart discovered the important 
fact (amply confirmed by its simultaneous discovery by Roth, Bugarsky, and Tangl, 
etc.) that the limiting surface of the red corpuscle offers an extremely high electrical 
resistance, when immersed in its natural surrounding fluid, the blood plasma. 
The ions contained within the blood corpuscles in solution are capable of free 
movement within the confines of their walls, as is shewn by the osmotic pressure which 
they are known to be capable of exerting upon them. Conduction of an electrical 
current would therefore also freely take place within the corpuscular walls. Observa- 
tions therefore which place the corpuscles in the position of poor or non-conductors can 
be used in evidence against the conductivity of the walls themselves, since they cannot be 
directed against the contained solutions. 
Ions moving through the blood plasma in the orderly conduction of an electric 
current are stopped by the surfaces, and do not penetrate the mass of the red corpuscles. 
In other words, the limiting surfaces are only partially permeable membranes, even if 
not strictly semi-permeable membranes ; and this statement so made is amply con- 
firmed by evidence of a different kind. For such experimental evidence is only an 
additional confirmation of a long well-known fact, that the inorganic salts of the plasma 
and of the blood corpuscles are not the same, and of the corollary which this fact 
implies, namely, that the walls of the blood corpuscles form barriers to diffusion processes 
between the solutions within and without them. 
