July 15, 1920 



Presoak Method of Seed Treatment 



367 



it appeared too injurious to germination to be of any practical value in 

 the field. A total of 6,300 seeds of three varieties was treated in this 

 series and planted in flats in the greenhouse. Records of germination, 

 counting all seedlings above ground on the seventh day after planting 

 for experiment I and those above ground on the ninth day for experi- 

 ments II and III, are given in Table II. 



Table II. — Effect of formalin treatment on germ,ination of wheat seed 



Treatment. 



Control 



Formalin i : 400 for 3 



hours 



Formalin i : 400 for 6 



hours 



Formalin 1:400 for 12 



hours 



Formalin 1:200 for 3 



hours 



Formalin 1:200 for 6 



hours 



Formalin 1:200 for 12 



hoiu-s 



China. 



Average percentage of 

 germination. 



Exp. Exp 

 I. II. 



Exp 

 III. 



63 

 40 



45 

 46 



68 

 48 

 46 



58 

 27 



35 

 43 



Bluestem. 



Average percentage of 

 germination. 



Exp 

 I. 



Exp. 

 II. 



53 

 26 



34 

 33 

 19 

 17 

 16 



Exp 

 III. 



49 

 27 



31 

 37 

 14 

 15 

 13 



Turkey. 



Average percentage of 

 germination. 



Exp 

 I. 



56 

 42 

 48 

 50 

 23 

 17 

 34 



Exp. 

 II. 



Exp 

 III. 



Aver- 

 age. 



65 



SI 

 54 

 57 

 27 



25 



35 



The preceding table shows grave injury to germination where the 

 stronger solution was used. There was also marked retardation of 

 germination. Formalin i to 400, while much less harmful, caused an 

 appreciable decrease in germination as compared with the controls. It 

 was observed, however, that the 12-hour treatment (1:400) invariably 

 produced less retardation and loss in germination than the 3-hour treat- 

 ment. This was repeatedly evident for each variety (PI. 69). A 

 fourth test for Turkey wheat (part of experiment IV), using 400 seeds 

 treated with formalin i to 400 for i hour, 400 seeds treated 12 hours, 

 and 100 seeds untreated, gave on the sixth day after planting 45 per 

 cent germination for the i-hour treatment, 59 per cent for the 12-hour 

 treatment, and 62 per cent for the controls. These results, so contrary 

 to what might have been expected, led to the experiments to be described. 

 A search of the literature after these results had been obtained disclosed 

 a similar condition in a number of cases not commented on by the 

 authors — that is, less injury from long exposures than from short ones. 



Such a condition is found in an analysis which I have made of the 

 data presented by a subcommittee of the War Emergency Board of 

 Plant Pathologists (4) on the effect of formalin i to 320 acting for various 

 periods on different cereal seeds. With wheat, in 18 tests out of 25 



