1921] MEIER—ROOT TIP | 135 
the opposite end of the cell. This statement, however, may apply 
to the chromatin. No theory is advanced as to why neighboring 
cells behave variously in this regard. The relative hydrogen ion 
concentration of the different parts of the cell no doubt plays a 
large part with reference to its reaction to the current. The 
assumption is generally made that cytoplasm is weakly alkaline. 
This conception is probably based on the reaction of the cell sap; 
nevertheless we have evidence that the migration of the protein 
constituents in the cells is toward the positive electrode. Likewise 
it is in accord with Harpy’s (9) results in treatment of a derived 
albumen, first with acid, then alkali, and a consequent change in 
direction of migration as previously stated. That the chromatin 
under some conditions bears a positive charge seems to be suggested 
by my own experimental evidence. That the migration of proto- 
plasmic particles, as influenced by the current, is due to the particu- 
Jar electrical charge of the constituent colloidal particles also 
seems probable, and would suggest that the cytoplasm carries (in 
the roots of the plants used in this study) always a negative charge. 
Summary 
1. A method of subjecting roots in moist air to the direct 
electric current has been devised which makes it possible to control 
and accurately measure the current actually flowing through the 
root. There is no evidence that under such conditions roots behave 
differently from those in soil or liquid if subjected to the same 
current intensity. 
2. Combinations of current intensity and time factors have been 
determined for producing death of the cells of roots, and the death 
curve plotted. 
3. Cytological preparations of treated roots show a migration 
of cell contents (with few exceptions) toward the positive electrode. 
4. The migratory effect (transfer of material) is not the same 
for all regions of the root. With one-tenth of time of death current, 
the cells immediately back of the root cap show little effect, those 
a little older (r mm. back) greatest effect, and the cells with large 
vacuoles no or little effect as to cytoplasm. 
