Juty 19, 1918] 
eompletes the activation. This view at once 
explains why the electric current is the most 
universal stimulating agent. It is well known 
that stimulation of any cell, by whatever 
means induced, is always accompanied by an 
electrical variation of the cell surface, or cur- 
rent of action; and we find the same to be true 
of the propagation of the excitation wave. This 
last process, which is evidently essential to the 
stimulation of the cell as a whole, is appar- 
ently dependent upon the bioelectrie circuit 
formed at the boundary between the active and 
inactive regions of the cell surface; that part 
of the local current which traverses the still 
inactive regions stimulates these electrically; 
the regions thus secondarily excited act sim- 
ilarly upon the resting regions next adjoining ; 
the process repeats itself automatically at each 
new active-inactive boundary as it is formed, 
and in this manner the state of excitation 
spreads continually from active to resting 
regions. A wave of activation thus travels 
over the surface of the element." 
Tf this theory of conduction is well founded, 
the chemical alteration of a surface film of 
material under the direct influence of local 
electrical circuits would seem to be indicated 
as the essential basis for the transmission. 
Changes of this kind are in fact a frequent 
phenomenon at the surfaces of metals in con- 
tact with solutions; and in a recent paper? I 
have called attention to the many striking 
analogies between the effects of such local 
electrolytic action in metals and the effects of 
local stimulation in living cells. For example, 
in the rusting of iron in aqueous solutions the 
formation of local electrical circuits between 
different regions of the metallic surface is 
now generally recognized to be the chief 
factor in the process. The surface layer of 
metal is typically not homogeneous, but ex- 
hibits local anodal and cathodal areas; at the 
former regions the ions of the metal enter 
solution and are precipitated as oxide or car- 
bonate, while nascent hydrogen and alkali are 
presumably formed at the cathodal regions. 
1 Cf. Amer. Jour. Physiol., 1915, Vol. 37, p. 348; 
1916, Vol. 41, p. 126. 
2 Loc. cit., 1916. 
SCIENCE 53 
Each of the areas of local chemical action thus 
represents an electrode-area in a local elec- 
trical circuit; and electrolysis at these areas 
is what determines the chemical changes there 
taking place. Now electrolysis is a process 
in which the transmission of chemical in- 
fluence to a distance without transfer of mate- 
rial is an essential and constant characteristic; 
the very flow of the current depends in fact 
upon this condition. Any electrochemical 
change at one electrode of a battery or other 
electrical circuit due to chemical action neces- 
sarily involves a corresponding change of a 
chemically opposite kind at the other elec- 
trode. Oxidation, the general effect at the 
anode, thus involves simultaneous reduction 
at the cathode; an oxidizing substance placed 
in contact with one electrode will thus in- 
stantly oxidize a reducing substance at the 
other electrode. Spatial separation of the two 
regions is a matter of indifference except in 
so far as it increases the electrical resistance 
of the circuit, thus retarding the rate of the 
electrochemical process. The transmission of 
the chemical influence between the electrodes 
is automatic and instantaneous. 
This “ chemical distance action’? suggests 
a possible basis for the protoplasmic type of 
transmission, since distance action is a fea- 
ture of all electrochemical circuits, including 
those present in local action at metallic sur- 
faces. If therefore it could be shown that the 
cell surface can act like a metallic surface the 
essential difficulties of the problem of proto- 
plasmic transmission might be regarded as 
overcome. An inconsistency, however, appears 
in the fact that the transmission of electro- 
chemical influence in a circuit is instantaneous 
(i. e., 3 X 10° em. per sec.), while the most 
rapid protoplasmic transmission—in the motor 
nerves of mammals—is only 120 meters per 
second; again, the intensity of chemical dis- 
tance action decreases with the distance be- 
tween the electrodes, because of the increase in 
electrical resistance, while in the nerve im- 
pulse there is normally no decrease in inten- 
sity (or “decrement”) as the local change 
3 Cf. Ostwald, Zeitschr. physik. Chemie, 1891, 
Vol. 9, p. 540. 
