juiyi5. I920 Presoak Method of Seed Treatment 379 



A half bushel each of Dietz and China wheats in bushel bags were 

 soaked in water 10 minutes, drained, and covered 6 hours, then soaked 

 in formalin i to 320 for 10 minutes, drained, and covered 6 hours. A 

 similar treatment was made on like quantities of seed, using copper sul- 

 phate I to 80 for K hour after the 6 hours' presoaking, followed by milk 

 of lime. The upper and central parts of each half bushel were dried, 

 and each of the eight lots thus obtained was planted in 10 rows of 300 

 seeds each. Suitable controls and seeds treated without presoaking were 

 also planted. 



At the same time, a bushel of Currell wheat, piled up on canvas, was 

 sprinkled with water and covered for 6 hours. Half of this was then 

 sprinkled with fonnaUn i to 320 and covered for 6 hours. The other 

 half was sprinkled \vith copper sulphate i to 80, covered X hour, and 

 Umed. Seeds from top and center were dried and planted, along with 

 controls and seeds sprinkled without presoaking. The results obtained 

 a month after planting are recorded in figure 6. 



The presoak-treated seeds again showed a marked improvement in ger- 

 mination over seeds treated without presoaking. Seeds from the center 

 of the bag are apparently affected to some extent, probably through lack 

 of aeration and the accumulation of carbon dioxid ; but the average ger- 

 mination of the presoak-treated seeds is better than that of the seeds 

 treated without presoaking. 



The sprinkling method at first sight appears to possess a distinct ad- 

 vantage over the soaking method. In the former, compared to controls, 

 there is a marked increase in germination of seeds sprinkled first with 

 water and after six hours with the disinfectant. This is most probably 

 due to the incompleteness of the sprinkling method, since the disin- 

 fectant can not reach each kernel as in the soaking method. Hence a 

 large number of seeds, affected only by the water vapor of the prelim- 

 inary sprinkling, receive the stimulation due merely to the absorption of 

 water and drying before planting. 



EFFECT OF PRESOAK METHOD ON BACTERIUM TRANSLUCENS VAR. UNDU- 



LOSUM 



EFFECT OF SIX hours' PRESOAKING FOLLOWED BY FORMALIN I TO 400 TREATMENT ON 

 BLACKCHAFF BACTERIA ON SEEDS PLANTED ON NUTRIENT AGAR 



A series of experiments was carried out parallel with the germination 

 experiments, using 2,360 seeds, to determine whether the 6-hour formalin 

 treatment when preceded by a 6-hour presoak would destroy or prevent 

 the growth of the blackchaff bacteria. Heat-sterilized wheat seeds 

 were heavily inoculated, using four virulent isolations of the blackchaff 

 organism, and dried overnight as before described. The next day the 

 seeds were placed in tubes of sterile tap water, which was drained off 

 after 10 minutes. The tubes containing the seeds were placed in moist 



