526 
Journal of Agricultural Research 
Vol. XIV, No. la 
Since Ewart published his papers, other investigators have put out 
results which seem to controvert his conclusions. Pickholz, * 1 by storing 
over sulphuric-acid solutions and by drying over concentrated sulphuric 
acid in vacuo , varied the moisture content of Kentucky bluegrass seed 
from a mere trace to 32 per cent. The lower the moisture content at the 
time of beginning the germination test, the more rapid and complete 
was the germination at 20° C., though germination was little affected at 
28°, or with a daily alternation between 20 and 28°. Seeds with a mere 
trace of water present germinated almost as well at the usually very 
unfavorable temperature 20°, as with the favorable alternation between 
20 0 and 28°. Waggoner, 2 by drying first at 6o° and later at ioo° C., 
reduced the moisture content of radish seeds to 0.4 per cent without 
affecting subsequent germination. 
EXPERIMENTAL WORK 
The work of the present authors with seeds of a number of species of 
Gramineae corroborates the results of Pickholz and Waggoner. It should 
be noted, however, that some kinds of seeds are known to be unable to 
withstand even ordinary air-drying. Among these are the seeds of sil¬ 
ver maple (Acer saccharinum ), wild rice (Zizania palustris), the various 
species of willows (Salix spp.), and many water plants. 
In the winter of 1913 seeds of Kentucky bluegrass (Poa pratensis L.) 
of 90 per cent germinating capacity were dried in vacuo over calcium 
oxid (CaO) at room temperature. With 1.5 per cent of moisture remain¬ 
ing in the seeds there was no fall in germinating capacity or in germi¬ 
nating energy. With 0.2 per cent moisture the germinating capacity 
remained the same, but the germinating energy was considerably less. 
With 0.1 per cent moisture the germinating capacity had fallen about 
5 per cent, and the germinating energy was seriously reduced. One lot 
previously dried in a lime desiccator to o. 1 per cent of moisture was fur¬ 
ther dried in a vacuum oven at ioo° C. for six hours to remove the last 
trace of moisture. The germinating energy (see below) was thus 
reduced to one-half what it was with 0.1 per cent of moisture, and the 
seedlings produced were weak; but the percentage of seeds which ger¬ 
minated remained the same as before removing the last 0.1 per cent of 
the water. All of the germination tests were conducted in the Jacobson 
apparatus with a daily alternation of temperatures between 20° and 
30° C. All of the tests with a quick-germinating lot were continued for 
28 days, and the ratio between the percentage of germination at the end 
1 Pickholz, L. Sin beitrag zur frags uber die wirkung des lichtes und dbr intermittierEnden 
TEMPERATURE AUF DIE KEIMUNG VON SAMBN, SOWIB UBER DIE ROLLS DES WASSERGEHALTES DER SAMEN 
bbi dieser wirkung. In Ztschr. Landw. Versuchsw. Oesterr., Bd. 14, Heft 2, p. 124-151, 1 fig. 1911. 
Literaturverzeichnis, p. 150-151. 
1 Waggoner, H. D. the viability of radish seeds (raphanus sativus l.) as affected by high 
temperatures and water content. In Amer. Jour. Bot., v. 4, no. s. P- 299-313* 1 fig. 1917* Literature, 
p. 312*313- 
