26o RESEARCHES ON FUNGI 



paper blown away from the mouth of the side-pipe. As the blast 

 of air subsided, the tissue-paper returned to its former position and 

 again covered the mouth of the side-pipe. In some of the experi- 

 ments the tissue-paper was blown a distance of 1 cm. and, in the 

 most successful experiment, made with a fruit-body which puffed 

 with great vigour, the tissue-paper was blown a distance of 2 cm. 

 The blast of air in each experiment carried spores with it and the 

 spore-cloud could be seen being deflected laterally by the obstacle 

 of the tissue-paper. 



When a fruit-body puffs, it not only shoots away many tens of 

 thousands of spores but also vast numbers of drops of ascus-sap. 

 When about twelve fruit-bodies had puffed into the test-tube, so 

 much ascus-sap in the form of extremely fine droplets had fallen 

 to the bottom of the test-tube in the region lettered a in Fig. 124 

 that, when the tube was tilted, the hquid could just be caused to 

 run in the form of a shallow drop. A microscopic study of asci 

 before and after explosion goes to show that, in all probabihty, the 

 volume of ascus-sap shot out from any ascus is at least equal to the 

 volume of the eight spores and may possibly be greater, so that the 

 gathering of moisture on the base of the tube a was in accordance 

 with theoretical expectation. 



The Cause of the Blast of Air. — When an apothecium puffs, it 

 does not contract its rim or alter its general shape, and there is no 

 reason to suppose that the blast of air emerges from the apothecial 

 cavity. It seems most probable that the blast of air is brought into 

 existence by the forward movement of the spores and drops of ascus- 

 sap. It was calculated that from one fruit-body, which was found 

 to have all its asci empty after it had puffed, a milhon spores had 

 been discharged. Probably these million spores were accompanied 

 by at least a milhon drops of ascus-sap. From the fruit-body, 

 therefore, there were shot forward in the same direction some two 

 milhon projectiles. At the beginning of their flight from an apothe- 

 cium each of the projectiles, moving as it does at a high speed, must 

 drag a certain amount of air forwards. Very quickly the velocity 

 of each projectile is greatly reduced by the resistance of the air ; 

 and, by this time, we may suppose, the air has been bombarded by 

 the projectiles to such an extent that it moves forward en masse 



