82 TWELFTH REPORT. 



was N / 50. After being immersed in this for an hour, the yield was 

 72%. The same concentration could be used for Wheat. After a twenty 

 minute immersion, the yield was 88%. The concentration most useful 

 in the case of Cofti was found to be X / 10. The yield after an immer- 

 sion of one hour, was still 56%. N / 25 was better adapted to Mustm'd 

 than anv other concentration. After a twenty minute immersion, the 

 yield of good seedlings was 88%. 



The last disinfectant used was formaldehyde gas. Forty per cent 

 formaldehyde was put in an oi>en vessel placed on a glass plate, on 

 which the seeds were also placed. The whole was then covered with a 

 bell-jar. the edge of which, where it came in contact with the glass plate, 

 was given a coat of vaseline so as to- make tlie chamber air-tight. Both 

 dry seeds and seeds soaked for five minutes in water were used. The 

 dry seeds of Lupine had to be exposed for an hour and forty-five min- 

 utes before the germination percentage dropped; and then it had 

 dropped only to ninety-six. When the soaked seeds had been 

 exposed for forty-five minutes, the germination percentage dropped 

 to ninety-tAvo. Beyond these period*;, the vitality of the seeds 

 steadily decreased, that of the soaked seeds becoming zero after seven 

 hours, while the drv seeds retained their vitalitv an hour or two longer. 

 The relative effect of the gas on dry and wet seeds is clearly brought 

 out in the case of Pea. Dry seeds, exposed for fifteen minutes yielded 

 64% of good seedlings; while the soaked seeds yielded only 28%. To 

 obtain a yield of 64% in the case of the wet seeds, they could be ex- 

 posed for two minutes only. After a twenty-five minute exposure of 

 the wet seeds, only 16% of good seedlings were obtained; while the dry 

 seeds, exposed for an hoiu', still yielded 36%. Wheah' was found to be 

 less sensitive to formaldehyde than Peas. After an exposure of fifteen 

 minutes, the dry seeds yielded 92% of good seedlings; while the soaked 

 seeds still yielded 527f- A ten-minute exposure of the wet 

 seeds, also gave 92%. The dry seeds of Corn were consideral)ly more 

 resistant than Wheat; the soaked seeds only slightly so. Dry seeds, ex- 

 posed for an hour, yielded 80% of good seedlings, while wet seeds, ex- 

 posed for thirty minutes, yielded only 36%. The dry seeds of Mustard 

 could be exposed three times as long as the soaked seeds, and they 

 still showed an equal vitality. Thus dry seeds exposed for forty-five 

 minutes, and soaked seeds, exposed for fifteen minutes, both yielded 

 40% of good seedlings. Dry seeds, exposed for thirty minutes, yielded 

 68% ; while wet seeds, exijosed for the same length of time, vielded 

 only 24%. 



In the first column of Table I are given the names of the seeds; in 

 the second column the disinfectants; in the third column, tlie concen- 

 trations best suited for the different kinds of seeds; in the fourth col- 

 umn, the length of immei^ion of the seeds in the disinfectants which 

 would still give a fair percentage of good seedlings; in the fifth column 

 the germination percentage and in the sixth column are given the results, 

 as tested with the apparatus (see plate), of the action of the different 

 disinfectants on the fungi and bacteria on the seeds. As can be seen by 

 running over this column, only five lots out of twenty-five were found to 

 be sterile, each lot being treated differently. 



