1921] MEIER—ROOT TIP I31 
It is not contended that the death curve is sharp and definite. As 
the tables show, some roots were killed before the maximum was 
reached. This difference is undoubtedly accounted for by the 
variations in cross-sectional area of roots used. 
CYTOLOGICAL 
A rather definite cytological effect is produced in roots exposed 
to the current just long enough to produce death. Roots exposed 
for fifty-two seconds at 0.6 milliampere give a very similar picture 
to roots exposed for two and a half minutes at 0.3 milliampere, or 
any other point on the death curve. Similarly, roots exposed for 
any fraction of the time required to produce death at any amperage 
give a comparable picture with those produced by exposure for the 
same fraction of time required to produce death at any other 
amperage. This fact was established only after long experimenta- 
tion, and until then no comparable cytological results could be 
-obtained with various combinations of time and current. The 
direction of current through the root had no influence except in 
direction of migration. 
Best results in fixing were obtained by various combinations of 
Flemming’s fluid. Root tips immediately after treatment were 
placed in the killing fluid. The usual processes incident to the 
paraffin method were used, and the roots sectioned and stained in 
saffranin-gentian violet. Satisfactory staining was quite difficult 
to obtain, and the finer details of the treated protoplasts in most 
cases were difficult to distinguish. 
In a root exposed to the current just long enough to produce 
death, the cells of the central cylinder back of the root cap show 
fairly even distribution of cytoplasm, which, however, is coarsely 
granular compared with the controls. Many cells show a distinct 
migration of cytoplasm toward the positive electrode. It is in 
the nuclei, however, that the effect is more noticeable. The 
nucleolus may have been displaced in either direction, more cells, 
however, showing displacement toward the positive electrode. A 
majority of the nucleoli had become elongated in a direction at 
right angles to the long axis of the root, similar to that shown in 
fig. 3. The nucleolus frequently is elongated sufficiently to reach 
