174 BOTANICAL GAZETTE [march 



incubator in a similar manner by inserting the tubes through 

 perforations in the top. This avoided the main source of tempera- 

 ture fluctuation in the incubator, opening the door. 



After the seeds were heated they were sterilized by washing 

 for 2 or 3 minutes in a n/$o solution of silver nitrate. While in 

 this solution the seeds were stirred thoroughly in order to free them 

 of all air bubbles. Then they were washed thoroughly in sterile 

 distilled water to remove the excess of silver nitrate which would 

 injure the seedlings when germinated. Sckroeder (28, 29) has 



permeable 



many 



seeds confirmed his conclusions. The importance of sterilizing 

 the seeds is realized when we consider that in some cases the 

 germination was delayed as much as 20 days. Miss Muller (25), 

 in her work on germination of heated seeds, found that after 10 

 days seeds were either germinated or destroyed by mold. By 



some 



from 



growth for several weeks. 



After sterilizing and washing, the seeds were germinated in large 

 Petri dishes containing a layer of moist cotton covered with a 

 layer of filter paper. The dishes were sterilized at 140 C, and 



maintain 



conditions. 



tempera 



germination 



moisture 



from time 



time, and only very slight variations occurred in any one of the 

 3 moisture content experiments. The Duvel (15) method was 

 used parallel with the ordinary oven drying method and the two 

 gave concordant results. Since the Duvel method requires less 

 than an hour to make a test, it was possible to check the moisture 

 content before filling the tubes for each trial. 



Results 



The effects of heating seeds is well shown in table I, which is 

 a daily record of the germination of a time series heated at 87? 5 C. 

 Seeds were considered normally germinated when both root and 



