THE PHYSIOLOGY OF CELL-DIVISION GAS 
There is, however, the following possibility to be borne in mind; 
if the changes of potential between the exterior and the interior of 
the cell, e.g., in the action-current, are due to alterations in the 
electrical condition of the cell-surface consequent on increased 
ionic permeability of the boundary layer—as the membrane theory 
supposes,—it ‘is demonstrable that steep potential-gradients will 
momentarily exist between the superficial and internal regions 
of the cell at times of sudden increase in permeability ;* this con- 
dition may be an important or even main factor in the transport 
of material through the cell, either in absorption and secretion, 
or in mitosis. 'The phenomena of mitosis, indeed, appear particu- 
larly significant from a physiological standpoint because of their 
furnishing strong indication that potential-gradients between the 
interior and the exterior of cells do in fact exist at certain periods, 
which are presumably periods of increased permeability. The 
radiations accompanying the process have the disposition of the 
electrical lines of force; they may be‘distorted or displaced, when 
once formed, by mechanical or other means, but in general the 
resemblance is unmistakable. If this point of view can be sub- 
stantiated for mitosis, the significance of electrical forces in absorp- 
tion and secretion, and probably in metabolism generally, will 
appear in a new light, since in mitosis all of these processes are 
concerned. 
The significance to be attached to alterations of membrane- 
permeability in mitosis is thus, according to the above consider- 
ations, of a twofold nature: (1) the facilitation of interchange 
across membranes, and (2) the production, between different 
regions of the cell, of electrical potential-differences which play 
a direct part in the transport of material, besides being respon- 
_ sible for the characteristic radiations and spindle-formation. 
The view that the mitotic figure with its astral radiations and 
spindle fibers is the expression of electrical potential-differences 
between the superficial and internal regions of the cytoplasm, and 
between cytoplasmic and nuclear areas, is one which I have advo- 
cated for some time. The chief difficulty under which such a 
view has hitherto labored is that of accounting for the existence of 
23 Cf. my paper in Biological Bulletin, 1900, vol. 17, pp. 207, 208; also American 
Journal of Physiology, 1910, vol. 26, pp. 128, 129. 
