IOWA ACADEMY OF SCIENCES. 
75- 
object OF THE INVESTIGATIONS. 
It was desired to obtain four thermal death-points: 
1. The temperature at which spores of corn smut lose their 
power of germination when immersed for fifteen minutes in 
water kept at that temperature. 
2. The temperature at which spores of corn smut lose their 
power of germination when subjected for fifteen minutes to that 
temperature in a dry oven. 
3. The temperature at which corn loses its power of germ- 
ination when immersed for fifteen minutes in water kept at that 
temperature. 
4. The temperature at which corn loses its power of germ- 
ination when subjected for fifteen minutes to that temperature 
in a dry oven. 
Further it was desired to obtain information regarding: 
(a) The temperature at which the young corn plant first 
shows injury due to the seed having been immersed for fifteen 
minutes in water at that temperature. 
(b) The temperature at which the young corn plant first 
shows injury due to the seed having been subjected for fifteen 
minutes to that temperature in a dry oven. 
METHODS AND MATERIALS. 
The corn smut used was one year old, and all from the same 
ear of corn. It was germinated in sterilized cistern water in 
rubber cells. The corn used was of the variety, Iowa Gold 
Mine, and of high germinating capacity. In all cases the check 
kernels were from the same ear as the treated kernels. The 
corn was germinated in boxes of ordinary garden earth. For 
the determination of the thermal death-point of corn (dry heat) 
the kernels were placed in the drawer of a Naples bath. For 
determining the thermal death-point (wet heat) of both corn and 
smut, the drawer of a Naples bath was filled with water, and 
the corn and corn smut immersed in it when it became of the 
proper temperature. 
To obtain the thermal death- point of corn smut (which is 
above 100^ C) it was necessary to use a dry sterilizing oven. 
The smut was placed in a small tin thimble fastened to the end 
of a string, and when the thermometer in the top of the oven 
indicated the temperature desired, a cork in the top of the oven 
was removed, the thimble lowered quickly into the oven and the 
cork replaced. 
