342 RESEARCHES ON FUNGI 



accounted for by the smallness of the amount of energy transmitted 

 by the sound waves coming from the exploding asci and by the 

 well-known law of inverse squares, namely, that the intensity of 

 the sound travelling outwards in all directions from a given source 

 varies, when heard by the ear, inversely as the square of the distance 

 of the source of sound from the ear. 



Taking advantage of the audibility of puffing in Rhizina inflata, 

 one can tell in the dark, merely by hstening and without using one's 

 eyes, whether or not spore-discharge is taking place. Thus I kept 

 some fruit-bodies for three days in a dark room. When, at intervals, 

 I took them out of their dishes in the dark and put them successively 

 to my ear, they puffed audibly just as they had done in the light 

 in the laboratory. I could not see the fruit-bodies, but my ears 

 assured me that their spore-discharging function was being vigorously 

 carried out. These experiments in the dark room show incidentally 

 that puffing is not dependent upon light. 



The sound of puffing is a collective sound made up of the indi- 

 vidual sounds produced by the explosion of the individual asci, 

 and is comparable to the fizzing sound made by the bursting of the 

 individual bubbles arising in freshly poured effervescent beverages. 

 I beUeve that it is possible to hear even the individual asci explode. 

 I put a fruit-body against my ear in a very quiet closed dark-room, 

 and Hstened attentively to the later phases of the puffing 

 phenomenon. The sound, after a short time, became discontinuous 

 and comparable to the sound made by the first few large rain-drops 

 faUing at the beginning of a thunderstorm upon a tin roof. Just 

 as one can hear each individual drop of rain under the conditions 

 just described, so I thought I could hear each single ascus explode 

 as puffing was ceasing. 



The hissing sound produced by the puffing of Puslularia catinus, 

 Aleuria vesiculosa, etc., is comparatively loud, but has a duration 

 of only about two or three seconds. On the other hand, the 

 effervescent sound produced by the puffing of Rhizina inflata is 

 comparatively feeble, but has a duration of from about one to 

 several minutes. Fruit-bodies of the Rhizina, kept in a closed 

 crystalhsing dish for a day and then taken out and placed close to 

 the ear, usually puffed audibly for upwards of a minute. One such 



