390 Bay/iss. — On the Galvcinotropism of Roots, 
alkaline diffusion from the respective poles the faintly alkaline gelatine was 
tinged slightly with phenolphthalein. After about twenty hours the roots 
in the strongly alkaline and acid zones near the negative and positive 
electrodes respectively, showed curvatures towards those electrodes, and 
after a further twenty hours the roots in the intermediate regions curved 
also but to a lesser degree, and then chiefly to the negative electrode. 
Thus, in one experiment, with 15 seedlings after 48 hours, 9 curved 
to the alkaline pole, 2 to the acid, and 4 remained straight, while with 
another set of 1 1 seedlings, 5 curved to the alkaline pole, 4 to the acid, and 
2 did not curve. These radicles were situated at distances varying from 
Fig. 1. Seedlings growing in gelatine. 
•5 to 12 cms. from the electrodes (see Fig. 1). For some experiments the 
gelatine was rendered slightly acid by a few drops of H 2 S 0 4 . The greater 
number of curvatures were still to the alkaline pole, even in the inter- 
mediate region, which was now slightly acid instead of alkaline. 
To ascertain how far geotropic irritability was affected by growth 
in gelatine, a few seedlings were laid horizontally in that medium, and 
compared with a control set grown in a damp, well-aerated vessel. After 
seventeen hours the control seedlings had curved nearly 90°, while those in 
gelatine were still straight ; and only after two days did the latter begin to 
curve slightly, no doubt because their geotropic sensitiveness was in large 
measure suppressed by lack of proper aeration. 
Some of these experiments were now repeated, using 4 per cent, 
gelatine with holes cut in and kept open by means of small chips of wood. 
Here the better aeration brought about a quicker response, for the roots in 
the zone intermediate between the strongly acid and alkaline zones showed 
decided curves within the first twenty-four hours after the current had been 
put on. 
