142 RESEARCHES ON FUNGI 



expand their pilei and freely liberate their spores in mushroom- 

 caves where the temperature is very constant and radiation from 

 the sun is excluded.^ 



(3) Certain small species of Coprinus belonging to the e'phemerus 

 group exhibit a marked periodicity in their development, which 

 is of such a kind that the fruit-bodies shed their spores only during 

 the night. These fruit-bodies, therefore, cannot possibly be radio- 

 sensitive.2 



(4) Coprinus sterquilinus has a continuous spore-discharge 

 period of several hours (8-12 hours in large specimens). A fruit- 

 body begins to shed its spores, not necessarily in the morning, but 

 at any time during the day or night. The spores are shot from 

 their sterigmata into the air between the interlamellar spaces, 

 other things being equal, as well by night as by day. The process 

 of autodigestion of the gills from below upwards takes place both 

 in darkness and in light. The rate of evaporation of the liquid 

 products of autodigestion at the free edges of the gills depends 

 merely upon the hygroscopic state of the atmosphere, the tempera- 

 ture of the au-, the speed of the wind, etc. Direct radiation from 

 the sun under field-conditions doubtless warms the pileus, hastens 

 somewhat the speed with which the zone of spore-discharge passes 

 up the gills, and hastens the rate of evaporation from the gill-edges ; 

 but such warming is not a necessary condition for successful spore- 

 discharge. In my laboratory at Winnipeg, where C. sterquilinus 

 has been grown for some fifteen successive years, the fruit-bodies 

 are never exposed to direct sunlight and yet they discharge their 

 spores into the air in a perfectly normal manner. 



The production and liberation of spores in the Coprini is essen- 

 tially a phenomenon of growth which, like other growth-phenomena, 

 is dependent on temperature. A rise of temperature below the 

 optimum, however caused, hastens the development of the basidia 



1 Observations made by the author in the mushroom-caves at Paris. 



- Two of these species come up spontaneously on horse dung in my laboratory 

 and I have had them under observation for many years. Also in upwards of one 

 hundred pure horse-dung cultures of Coprimis lagopus, made from spores in wide 

 tubes, Mr. W. F. Hanna and I noticed that, under the laboratory conditions prevail- 

 ing, the fruit-bodies always opened their pilei about midnight and freely shed most 

 or all of the spores before the next daj' dawned. 



