404 Bayliss . — On the Galvanotropism of Roots . 
them in vertical and horizontal positions. The seedlings were either fixed 
in narrow glass troughs or pinned with brass or silver pins to very thin 
sections of cork, covered with cotton wool, and were kept moist by frequent 
supplies of water of suitable temperature. The room was kept at a tempera- 
ture of about 23° C., but a thermometer inserted among the seedlings during 
the exposure to magnetic action registered 25° C. The seedlings were 
arranged as close as possible to the poles without touching, and kept 
in that position 40 min., 60 min., 2 hrs., 4 hrs., or 6 hrs. ; in every experi- 
ment light was excluded, and a control was arranged. 
When the roots were removed from the magnetic field and examined, 
some were transferred to a clinostat for twenty-four hours, and others were 
fixed in chrom-acetic acid, and, after the usual treatment, microtome 
sections obtained. 
These experiments gave only negative results ; hence it seems quite 
conclusive that to produce any influence on the growth of roots a very 
much more powerful magnetic field would be necessary. 
Microscopic examination of the microtome sections fails to give 
evidence of any change or alteration in the position of the cell contents : 
also, since in a few experiments, though not in the majority, the geotropic 
curvatures of the roots placed horizontally just above one pole slightly 
exceeded those of the roots placed horizontally just below, special attention 
was directed to the position of the statoliths in the root-cap ; but no 
difference between either set and those of the control roots was to be 
noted. 
Some further experiments were carried out at an electric light station, 
using the magnetic field produced by a small dynamo through which 
passed a current of 25 amperes produced from an E.M.F. of 250 volts. 
The roots were exposed to magnetic action for twenty-five or twenty-nine 
hours at a temperature of 24° C. Here again no positive results were 
obtained. 
I should like also to make brief reference to the recently published 
work of Dr. Gustav Gassner (Bot. Zeit., Sept. 1906) on ‘Der Galvano- 
tropismus der Wurzeln.’ 
His method of experimenting was as follows: — A seedling was fixed 
in a vessel of definite size (20 x 9 x 8-5 cms.) with its root immersed in water 
or sometimes gelatine : using carbon electrodes, a current of known strength 
was passed through the water or gelatine and so through the root for periods 
of time varying from a few seconds to fifteen hours or more : the current 
density seems to have varied between *005 and 4* 5 M. A. per qcm. 
He arrived at the conclusion that Galvanotropism was nothing more 
than a special case of Traumatropism, and that the + or — direction 
