728 RALPH 8. LILLIE 
tivity the longest. The time during which this gradient will 
persist will be that required for the diffusion of ions to equalize 
the potentials. This diffusion is probably slow in the viscous 
protoplasm filled with colloidal particles, so that the gradients 
may persist for a considerable period. The space-relations of 
the regions of highest and lowest potentials would be approxi- 
mately as represented; the region most remote from the two posi- 
tive central and peripheral areas will naturally remain negative 
relatively to these areas for the longest period; this region will be 
intermediate in position in each half of the cell. Each hemisphere 
is thus the site of two oppositely oriented electrical fields. The 
potential-gradient of these fields, as the above considerations 
show, may at their first appearance be many volts per centimeter; 
their duration is problematical, but it seems probable that they . 
would have marked effect, even if acting for only a few seconds. 
The influence on the colloidal particles is apparently to produce 
electrical polarization analogous to that of most indifferent 
particles in strong electrical fields; the particles assume positions 
along the lines of force and apparently in many cases fuse to form 
fibrils. These fibrils once formed may _ persist, in accordance 
with their colloidal nature, for some time after the originating 
conditions have disappeared.® It should be noted that the defi- 
nite character and sharp curvature of the rays connecting the 
astral and nuclear areas receive consistent explanation on the 
present theory, since the nuclear area is positive and the astral 
®2 It should perhaps be emphasized that colloidal fibrils once formed may out- 
last the disappearance of the conditions to which they owed their origin. The 
essential process in their formation is the fusion of colloidal particles to form 
larger aggregates, as in coagulation. Now all degrees in the reversibility of the 
coagulation-process in protein solutions are known; some coagula (e.g., those 
produced by alkali or alkali-earth neutral salts) are readily, others difficultly 
reversible (heavy metal coagula). The fibrils formed in mitosis are often remark- 
ably persistent (Zwischenkérper, etc.). It is clear then that once having been 
formed they may undergo curvature, displacement, or crossing, and the fact that 
they often do so under normal or experimental conditions (ef., e.g., Morgan: 
Proceedings of the Society for Experimental Biology, 1910, vol. 7, p. 132) in no 
way invalidates the theory that their formation is due to electrical conditions 
like those imagined above. 
