48o RESEARCHES ON FUNGI 



The Effects of High and Low Temperatures. — On November 19, 

 in the wood-shed, I found some large fruit-bodies of Pleurotus 

 ostreatus projecting from the sides of one of the Poplar logs. The 

 air was still and the diffuse daylight available fairly strong. On 

 watching intently one of the largest fruit-bodies against a black 

 })ackground, I distinctly saw with the naked eye tiny white spore- 

 clouds coming slowly away from the gills. On November 22 I 

 repeated this observation. For November 19 and 22 the maximum 

 temperatures were 46° F. and 44° F. respectively, and the minimum 

 temperatures both 42° F.^ At noon on November 25 and some 

 other days when the temperature was decidedly lower, spore- 

 discharge from the pileus was invisible. The evidence seemed to 

 indicate that only on relatively warm days was the emission of the 

 spores sufficiently rapid to enable one to perceive the spore-clouds. 

 The only otlier species of Agaricineae from which I have as yet seen 

 spores escaping from the gills under natural conditions is Annillaria 

 mellea.^ 



During the night of November 24 there was a slight frost, and 

 November 25 was a cool day with maxinmm and minimum temper- 

 atures of 40° F. and 28° F. respectively. At noon on November 24 

 I was unable to perceive spores being given off from the fruit-bodies 

 on the log. At 1.80 p.m. I gatherer] one of the fruit-bodies and set 

 it in a room where the temperature was about 70° F. At 9 p.m., 

 with the help of a beam of light given out by the electric hand-lamp 

 described in the preceding Section, I was easily able to see clouds of 

 spores coming away from the gills. Thereupon T went out to the 

 wood-shed where the temperature was about 32° F. and, with the 

 aid of the lamp, attempted to observe the escape of the spores from 

 the fruit-bodies remaining on the log, but all in vain : no trace of 

 spore-clouds could be seen. It was surmised that the inactivity of 

 the fruit-bodies on the log was due simply to their low temperature. 



At 9 P.M. on the same day (November 24) I gathered another 

 fruit-body from the log. This fruit-body had a temperature of 

 about 32° F. and, when tested with the lamp for the emission of 

 spore-clouds, gave negative results. At 9 p.m. I therefore was in 



' Records taken at the Midland Iiiwlitiite C)I)i-ervatorv. Edgbaston. Birmingham. 

 - Vide these Resmrches, vol. ii, 1922. pp. 101-102. 



