HELIOTROPISM OF ASCI IN DISCOMYCETES 303 



on which it was growing and transferred it to a small crystallising 

 dish covered with a glass plate. On three successive days thereafter 

 I removed the plate and quickly took out the fruit-body from the 

 dish. Each time, on coming into contact with the dryer outer air 

 of the laboratory, the fruit-body puffed vigorously. The blast of 

 spores was emitted for 1-2 seconds and could be readily heard. 

 Falck ^ states that, in Aleuria vesiculosa, puffing cannot be caused 

 by a rise of temperature but can be caused, at first, by touching the 

 hymenium with a solid object or by stroking it with a hair-pin and 

 also, later, by blowing upon it. Whether or not my fruit-body 

 puffed because it was touched, or because air passed rapidly over 

 its surface, or because the tips of its asci were exposed suddenly to 

 dry air was not determined. 



PuflRng of Aleuria vesiculosa under Natural Conditions. — Dr. 

 H. T. Giissow has seen fruit-bodies of Aleuria vesiculosa puff inter- 

 mittently when growing under purely natural conditions and 

 untouched by man. His observations, which he kindly communi- 

 cated to me in litt., were as follows. " Toward the end of August, 

 1928, 1 sat on the shore of Penlake, Muskoka, in Ontario, underneath 

 hemlock, spruce and maple. The ground was very moist and the 

 fungus flora plentiful. Occasionally, with the swaying of the 

 branches, a sunbeam or two flitted across the ground to disappear 

 again and throw things into a dense shade. In the light of a 

 sunbeam something like a sparkling cloud was thrown straight up. 

 I looked more closely. Perchance it was a falling drop of water 

 splashing ; but no, there was nothing to see ! Another cloud was 

 shot up not more than forty inches from my eyes, and then I 

 perceived that it had come from the Waxy Peziza, Aleuria vesiculosa, 

 wonderfully camouflaged against the debris of the ground. I watched 

 the fungi for some minutes. Deep shade, Nothing happened. 

 There ! A sunbeam momentarily fell upon the cups, and at once 

 there was a puff of glistening sparks ! Soon the sun began to shine 

 directly upon the cups and then, twice in succession, more clouds 

 of spores appeared. Would puffing take place in the shade ? I held 



^ R. Falck, " Ueber die Sporenverbreitung bei den Ascomyceten. II. Die 

 taktiosensiblen Di.scomyceten," in his Mycologinche Untersuchungen unci Berichte, 

 Cassel, Bd. 1, Heft III, 1923, p. 374. 



