1896] TOXIC EFFECT OF ACIDS AND SALTS UPON PLANTS 127 
first the method of germination. The peas were placed in a 
beaker, covered with distilled water and allowed to soak for 
twenty-four hours; they were then placed in a Petri-dish 
between moistened sheets of filter paper and allowed to remain 
until the radicles just burst through the seed coats. In all the 
experiments it was important that the seedlings should have 
Straight roots, since it was necessary to measure the roots at 
intervals to determine the growth. If the peas were allowed to 
remain between sheets of moistened filter paper the roots grew 
crooked and twisted and could not be used, so it became necessary 
to resort to other methods of growing them. 
Two different methods were used, both of which were quite 
Satisfactory. 
1. A thin sheet of cork was perforated by means of a cork- 
borer with a series of holes as shown in the diagram (jig. 7), 
the large opening being just small enough to keep the pea from 
slipping through. This cork was then floated ina deep Petri-dish 
of distilled water, and as soon as the radicle had burst through the 
seed coats the peas were transferred to the cork. The peaswere 
so placed that the radicle was directed toward the small opening 
of the cork, and the whole was covered with a sheet of filter 
Paper which hung down into the water and thus kept the peas 
moist (fig. 2). The peas were then allowed to grow until 
they were of sufficient size for use in the experiments. In cases 
where germination was slow it was found necessary to change 
the distilled water several times before the seedlings were of suf- 
ficient Size for use. In the majority of seedlings the roots grew 
quite straight. 
2. Another method, quite similar to the above, was also used. 
Two sheets of cork were taken; one was provided with openings 
Somewhat larger than the pea; the other sheet of cork was pro- 
vided with smaller openings which would register as shown in 
diagram when the two corks were placed one above the other 
8-3). The two sheets of cork were then wired together and 
the small openings were provided with glass tubes about 5% 
long. The whole was placed in a deep dish and the peas were 
