HELIOTROPISM OF ASCI IN DISCOMYCETES 269 



two false assumptions : (1) that the asci in the hymenial chambers 

 and folds are not heliotropically curved but are straight ; and 

 (2) that the air-currents produced during puffing are caused by a 

 difference in temperature between the fruit-body and the outer air. 

 In the preceding Chapter, I have shown by means of a simple 



Fig. 128. — An experiment on spore-discharge in Gyromitra 

 esculenta. A fruit-body with ripening asci has been kept 

 in a moist chamber. A pencil of rays from an incandescent 

 lamp is now suddenly directed on to the fruit-body. The 

 fruit-body reacts to being heated by emitting spores vigor- 

 ously. The clouds of spores rise in the chamber and some of 

 the spores settle on the glass slides suspended therein. Copied 

 for the author by G. Atkinson in black-and-white from Olga 

 Falck's half-tone drawing in R. Falck's Mycologische Unter- 

 suchungen und Berichte, Heft II, 1916, Fig. 1. 



experiment that, when a fruit-body of Sarcoscyj^ha frotracta, which has 

 not been warmed above the temperature of its surroundings, puffs, 

 the discharged spores which are shot out from the mouth of the 

 cup impinge upon the air, set the air in motion and, in the end, are 

 borne along by the air for a much greater distance than they would 

 go were the air to remain still. ^ The air-currents which Falck 

 perceived in his experiments with the Morchellaceae are doubtless 



^ Vide supra, pp. 257-260. 



