On the Galvanotropism of Roots . 1 
BY 
JESSIE S. BAYLISS, M.Sc. (Birm.). 
With Four Figures in the Text and two Curves, 
Contents. 
Section page 
1. Historical 387 
2. Preparation of material 389 
3. Experiments with seedlings growing in gelatine ........ 389^ 
4. Experiments with polarizable electrodes, directly applied to the root ..... 391 
a. Results with* weak currents 392 
b. Results with strong currents 393 
c. Summary of results with polarizable electrodes ....... 394 
d. The angle of curvature ............ 394 
e. The sensitive zone ............. 394 
f Decapitated roots 394 
g . Duration of stimulus . 395 
5. Experiments with non-polarizable electrodes directly applied to the root .... 395 
6. Action of local acid and alkali 395 
7. Latent period of response ............. 396 
8. The abnormal thickening of many roots .......... 396 
9. Abnormally elongated cells 397 
10. Rate of growth of stimulated roots 398 
a . Diagrammatic representation of the growth in length of curving roots . . . 398 
11. Experiments with acid and alkali diffusing through gelatine 399 
12. Summary of results 400 
13. Theory and critical 401 
1. Historical. 
E LFVING 2 observed that roots responded to electrical stimuli. He 
grew seedlings with the tips only of their radicles dipping vertically 
into water, between two electrodes, and found that the roots curved towards 
the positive electrode. He obtained the same result when the current 
traversed the root longitudinally and also with decapitated roots. With 
some seedlings (Lepidium, Sinapis , Raphanus) he could not get constant 
results, and with one ( Brassica ) the curve was always towards the negative 
1 An abstract of much of the work included in this paper was communicated to the Royal 
Society by Dr. Francis Darwin, Nov. 23, 1905. 
2 Elfving, Bot. Zeitung, 1882. 
[Annals of Botany, Vol. XXI. No. LXXXIIX. July, 1907,] 
