Bayliss . — On the Galvanotropism of Roots . 403 
as far as they go, the conclusions he draws from them need extension and 
amplification. 
Thus in regard to the — curvatures obtained by him with weak 
currents acting on roots arranged in water, the stimulatory effect of the 
travelling ions would preponderate, and of these the acid ones especially, 
which, impinging first on the sides of the roots facing the — electrode, 
would produce a curvature in that direction : convection currents, aided by 
those due to the rotation of the cylinder of water, would prevent any great 
accumulation of ions at the two electrodes, so there would be no strongly 
marked acid or alkaline zones as in gelatine, and hence there would be no 
+ curvatures. 
This arrangement of growing roots completely immersed in water 
is not a good one, since they must necessarily lack proper aeration. The 
curve to the + electrode obtained by using strong currents Brunchhorst 
considered to be of a traumatropic nature, because his roots, and Elfving’s, 
usually died : but this term is certainly inapplicable to all + curvatures, 
since it is quite easy to obtain them without injury : though it is quite 
possible that Brunchhorst’s and Elfving’s curves were really curves of 
injury. 
Also Spalding 1 has shown that traumatropic curvatures will take place 
even when growth is arrested for seven or eight days by means of plaster 
of paris imbedding ; whereas an electrically stimulated root, if allowed to 
remain as long as five days in a cast, will not curve after release. 
University Botanical Laboratory, 
Birmingham, 
May, 1906. 
Postscript. 
After the completion of the foregoing work on the Galvanotropism of 
Roots it seemed desirable to ascertain whether a powerful magnetic field 
would also produce stimulatory effects. It is well known that a plant cell 
is made up of constituents possessing different magnetic permeabilities, 
and hence, theoretically, a field of sufficiently great power could hardly fail 
to influence growth in some way or other. 
A horseshoe electro-magnet with adjustable pointed pole-pieces was 
used : each iron core was 7-95 cms. diameter, and its length 32 cms. 
A current of about 15 amperes, produced from twenty cells (the E.M.F. of 
each being 2 volts), passed through the coils, against a resistance of 
4*15 ohms. The pole-pieces were adjusted so that their distance apart varied 
from 7*5 cms. to 3-7 cms. in different experiments; and the roots of very 
young seedlings of Pisum sativum and Vida Faba were placed between 
Spalding, Annals of Botany, December, 1894. 
