I§2 
Fraser . — Parallel Tests of Seeds by 
Different samples of barley were very kindly sent for the purpose 
by Mr. Stapleton of Aberystwyth. 
(ii) Electrical Method . — The embryos were dissected from the grain, 
and connected to the circuit which Professor Waller describes in his paper 
on the vitality of seeds, in such a way that a current passing in the direction 
root — > stem causes a deflexion of the galvanometer from left to right. This 
direction is designated by the sign + , indicating a ‘ positive ’ response from 
B to A. 
The circuit consists of : 
(1) A compensatory circuit. 
(2) Two' galvanometers in series of greater and lesser sensitiveness 
respectively, the deflexions of which are thrown on to a specially constructed 
scale, which is then easily read. 
(3) An induction coil capable of giving single induction shocks of 
known strengths and direction. 
By a suitable arrangement of plugs any of these branch circuits can be 
short circuited. 
When the embryo is adjusted the galvanometer plug is opened, and any 
current in circuit due to the plant material noted. This is immediately 
balanced by throwing in, from the compensator, an equal current in the 
opposite direction to the accidental current. A standard for the electrical 
response is then obtained by ascertaining the deflexion of galvanometer 
caused by sending into the circuit o-oi volt from the compensator. From 
this the magnitude of the response can afterwards be calculated. The 
apparatus is adjusted so that the galvanometer deflexion is at zero. Next 
a single-break induction shock is sent into the plant, the galvanometer circuit 
being closed at the time of shock, and opened directly after, so that only 
the response of the plant may be recorded. A series of four shocks 
is applied, and the corresponding responses noted, the order in which they 
are given being: (1) + 1,000, (2) —1,000, (3) +10,000, (4) —10,000, in 
notation of a Berne coil supplied by two Leclanche cells. The response, 
if large, is read on the scale of the less sensitive galvanometer ; if small, 
on that of the more sensitive one. 
Any residual current aroused by an induction shock is balanced from 
the compensatory circuit before another is delivered. 
At the end of the series the value of o*oi volt is again recorded. 
This furnishes the routine of the experiments carried out, an average 
of ten experiments being taken as a rule. 
In Table I an example of ten experiments is given. 
Object of Experiments. 
To determine how far there was a correspondence between the average 
germination value and the electrical response. 
