6. The tolerance of dormant seed to heat treatment varied with the moisture content of the seed. Corn and barley seed with 24 per cent moisture was killed with one 30-minute treatment at 100° C. With a reduction of moisture content to 9 per cent the seed was not injured by a 30-minute treatment at 100° C, but after 60 minutes germination was only 30 per cent, and after 2 hours only 10 per cent of the seed germinated. Seeds with 5 per cent moisture germinated perfectly after 2 hours treatment at 100° C, but were killed after 30 minutes at 115° C. Seeds with 2 per cent moisture, the reduction in moisture content being accomplished by drying approximately 3 weeks at 60° C, germinated well after 30 minutes at 115° C, but only 10 per cent germinated after 60 minutes, and 30 minutes at 130° C killed all of the seed. The corn seedlings from the sub-lethal dosages at the different moisture contents were weak and chlorotic, many failing to survive, but the development of normal green color was not similarly altered in the barley seedlings.