88 BOTANICAL GAZETTE [ AUGUST 
tions.” The seeds were germinated in the usual manner. After 
being swelled in water they were placed in moist, loose cotton 
batting and set in the dark until the radicles had reached a 
length of from 2™ to 4™, when they were ready for use. 
Experiments were made with solutions contained in glass 
beakers of convenient size that were, of course, cleaned with the 
utmost care each time they were used. To support the seedling 
in proper position the following arrangement was used. Through 
a large cork fitting loosely over the beaker was thrust.a glass 
rod which played rather tightly through it. Another and 
smaller piece of cork (small enough to allow ample room about 
it in the beaker) was likewise tightly pushed on the rod. To 
the circumference of this inner cork the seedlings were secured 
by means of glass pins, and by sliding the cork support up o 
down on the rod they were set into the solution at the desired 
depth. The large cork, by closing loosely the mouth of the 
beaker, allowed sufficient change of air within, at the same time 
preventing undue evaporation from the solution. 
Since in the experiments the prime thing sought was the 
degree of concentration at which each solution just allowed the 
radicles to live, it became important to avail ourselves of all the 
means which would aid in deciding whether a radicle was living 
or dead. As Askenasy™ has pointed out, almost the only reli- 
able indication concerning the condition of a plant is its growth 
rate. Accordingly access was had to the well known method of 
Sachs.” A fine mark of India ink was made 15™" from the tip 
of the root, a distance safely including the entire growing zone 
of the radicle. Thus marked, the roots were placed in the 
solutions, set in the dark, and again observed after a perio 
of from fifteen to twenty-four hours. In order to deter 
© True, On the influence of sudden changes of turgor and of temperature me 
growth. Ann. of Bot. 9: 372. 1895, i 
*Askenasy, Ueber einige Beziehungen zwischen Wachsthum und Tempera 
Ber. d. deutsch. bot. Gesellsch. 8:75. 1 ; : 
Sachs, Ueber das Wachsthum der Haupt- und Nebenwurzeln. Arb. d. 
bot 
6% ut Wiirzburg 1: —. 1873, and Gesammelte Abhandlungen itiber Pflanzen-phys* 
ologie. 2:778. 1893. 
