RATE OF DEVELOPMENT OF INDIVIDUAL SPORES 57 



ment varies with temperature is provided by the following series 

 of observations. On August 12, 1922, which was a very cold day 

 for the time of the year, with a room temperature of about 

 58-60 F., the interval of time elapsing between the first 

 appearance of a spore on its sterigma as a tiny rudiment and its 

 discharge was found, as an average for five basidia, to be 2 hours 

 26 minutes. 1 The gill was left in the compressor cell overnight. 

 The next day, August 13, was sunny and relatively warm, so that 

 the room temperature was raised to about 70 F. New observations 

 were made and it was found that the interval of time elapsing 

 between the first appearance of a spore on its basidium and 

 its discharge was now only 1 hour and 34 minutes, a reduction 

 of 52 minutes as compared with the previous day. 2 Since the 

 observations on the two successive days were made on the same 

 gill confined within an undisturbed compressor cell, and since the 

 only difference in the conditions was one of temperature, it seems 

 clear from the results obtained that in Collybia radicata the indi- 

 vidual spores develop much faster at high temperatures than they 

 do at low ones. 



1 Observations spread over eight hours and made conjointly by myself and my 

 nephew, Bernard A. Workman. The basidia were all seen projecting beyond the 

 free edge of the gill. The intervals for the five basidia were : 2 hours 30 mins., 

 2 hours 25 mins. (measured by myself) ; 2 hours 22 mins., 2 hours 25 mins., 2 hours 

 30 mins. (measured by B. A. W.). 



2 The interval of 1 hour 30 mins. given in the first Table in this Chapter was 

 determined for another Collybia radicata fruit-body in 1916. 



