389 
Bayliss. — On the Galvanotropism of Roots. 
Further research of a less restricted character was obviously needed *, 
and this investigation was initiated and carried on in the Botanical 
Laboratory of the University of Birmingham, ”nder the direction of 
Dr. (now Professor) A. J. Ewart, to whom the author is greatly indebted 
for much kind and valuable assistance. She also wishes to express her 
thanks to Professor Hillhouse for the use of the resources of the Botanical 
Laboratory and for his kindness in criticizing the work, and also to 
Professor Poynting for the use of apparatus belonging to the Physical 
Department and for his help when referred to on points of technical detail. 
2. Preparation of Material. 
To prepare material for the following experiments seeds of Vicia Faba 
(both broad bean and horse bean), Phaseolus multiflorus , Zea Metis, Pisum 
Sativum , Helianthus animus, Helianthus giganteus , Cucurbita Pepo , and 
Ricinus zanzibarensis were soaked in water for usually twenty-four hours. 
The seeds after soaking were germinated for a further twenty-four 
hours in moist sawdust, then carefully withdrawn, and the germination 
continued for a time in a vertical position in a damp chamber so as to avoid 
the possibility of accidental or injury curvatures. As an alternative their 
germination was continued horizontally in a moist chamber which was 
rotated on a clinostat. 1 2 To ascertain whether the radicles grew, or not, 
after stimulation, the apical centimeter was marked with Indian ink into 
spaces 1 mm. wide. 
3. Experiments with Seedlings growing in Gelatine. 
Instead of using water, as in Elfving’s and Brunchhorst’s experiments, 
seedlings were arranged in a glass vessel containing 3 per cent, gelatine 
between two platinum electrodes, 10 to 12 cm. apart, and a current of 
4*2 voltage passed through. In order to trace the limits of acid and 
1 See Pfeffer, Physiology of Plants, vol. iii, Eng. trans., section 42. 
2 The clock clinostats used in these experiments are a hitherto undescribed adaptation, by 
Professor Hillhouse, of American eight-day clocks, in which the full eight-day working power is 
retained — a point of some importance in prolonged experiments, since disturbance for winding 
purposes is reduced to a minimum. The face, hour-hand, and spindle are removed, and a new 
toothed wheel on the minute spindle engages another wheel borne upon a new spindle, of the same 
thickness as the minute spindle, which is fixed upon the clock framework a short distance away. 
The rate of rotation of this second spindle depends upon the relative number of teeth in the two 
wheels. A perforated brass disc, or table, fits upon either of these spindles by means of a split 
sleeve, and thus each clock gives rotation at one-hour periods, and at longer or shorter periods 
according to construction. For safety, the face is replaced by a metal plate, pierced for spindles 
and key. To exclude water when in horizontal use, another plate, with slit for the spindle, can be 
slipped on. With vertical axis, this clinostat carries freely upon its rotating disc a weight of several 
kilos. Its use with horizontal axis is illustrated, in an extreme case, in the accompanying Fig. 2, 
a flat cork of suitable size being then attached to the disc by means of the perforations. In a more 
recent form of the instrument, each clock bears two supplementary spindles with different rates 
of rotation. 
F f 
