/an. 13 ,Forcing the Germination of Freshly Harvested Wheat 81 
The effect of drying and heating treatment depends to an extent not 
always recognized upon the condition of the grain at the time of treat¬ 
ing it, the temperature used, and the length of time the treatment is 
applied. Kiessling (28) found a beneficial effect upon barley in the 
early stages of after-ripening and a harmful effect in the later stages or 
after after-ripening was complete. Stapledon and Adams (59), with 
very mild dry heat treatments, secured beneficial results with good 
strong grain and harmful results with weak or diseased grain. Atter- 
berg ( 6) reported a decrease in germinating capacity as a result of dry¬ 
ing for a short interval, followed by an increase with longer drying. 
Wollny (45), working with fully afterripened cereals, found that arti¬ 
ficial drying decreased germination but increased the productivity of 
the resulting plants. According to Worobiew (46) heating wheat before 
germination promoted a xerophytic type of structure and increased pro¬ 
ductivity under drought conditions but had no effect with ample mois¬ 
ture supply. Apparently Johannsen’s failure (25) to induce the germi¬ 
nation of fresh two-row barley and Stapledon and Adams’ (39) only 
slightly favorable results with a number of cereals are to be explained as 
a result of drying for an insufficient length of time. 
The temperatures used for drying have varied from about 30° C. to 
as high as 8o° C., and the results with the higher temperatures have 
frequently been harmful on account of the relatively high moisture 
content of the cereals at the time the heating was begun. Muller (36) t 
Waggoner (. 42 ), Harrington and Crocker (20 ), Nagai (57), Atanasoff 
and Johnson (5), and others have shown that cereal and other seeds are 
quite resistant to the effect of temperatures even as high as ioo° C. if 
their moisture content is low when the heating commences. Zalenski 
(48) found 50° C. for a short time fatal to fresh green grain of winter 
rye and harmful to the grain in later stages of maturation. 
Several have found a temperature around 40° C. to be best for increas¬ 
ing the germination capacity of not after-ripened cereals. Stapledon and 
Adams (39) used this temperature for three days with limited effect. 
Hotter (24) gave 10 days, Hiltner ( 21 ) 8 to 10 days, and Atterberg (6) 
8 days as the length of time drying at 40° C. was necessary to bring 
not after-ripened cereals to their full germinating capacity. Atterberg 
obtained the same results from 8 days’ drying at 30° C. if the seeds were 
dried in a current of air, a fact which seems to indicate that oxygen sup¬ 
ply or rate of drying is important. Moritz and Morris ( 34 ) gave 43 0 C. 
as the maximum temperature to be used in kiln-drying barley for malting, 
and Hiltner stated that temperatures above 40° C. may be injurious to 
the fresh, relatively moist not after-ripened grain. Since barley is more 
resistant than the other cereals to the harmful effects of high temperatures 
40° C. would seem to be as high a temperature as could safely be adopted 
for general use. 
In the author’s investigations heating for one day at 40° C. was without 
effect upon the germinating capacity of very moist, fresh wheat. Table 
I shows the effects of other dry-heat treatments upon germination at 
room temperature. 
Drying "wheat eight days at 40° C. had a much more pronounced effect 
upon its subsequent germination than drying at the same temperature 
for five days. This drying treatment was more effective in hastening 
germination with barley than with wheat or oats, but it raised the germi¬ 
nation capacity to nearly 100 per cent in all cases. When the temperature 
