234 RESEARCHES ON FUNGI 



become redispersed by herbivora. In these species it is to be 

 expected that the structure of the ascus would be correlated with 

 wind-dispersal. 



The Dispersal of Spores by the Wind in some Ascomycetes. 

 According to Falck, 1 in Gyromitra esculenta one of the Helvel- 

 lacese the spores, after being shot out of the ascus, become 

 separated from one another and settle singly; and I have noticed 

 a similar phenomenon in Bulgaria polymorpha (Wettst.). Doubt- 

 less, in both these species, the spores, which are no larger than 

 those of many Hynienomycetes, are carried away from the fruit- 

 bodies by the wind. 



Plowright 2 watched the discharge of the spores of Morchella 

 gigas one evening with the aid of an oblique beam of sunlight. 

 He observed that the head of each Morel was surrounded by a 

 cloud of spores extending 3 or 4 inches around it. He states 

 that "This cloud could only be seen in the oblique light against 

 a dark background. When acted upon by a gentle current of 

 air, such as would be produced by gently waving the hand, it 

 swayed to and fro without manifesting any tendency to become 

 dispersed. The component sporidia were in constant motion, 

 rising and falling and circling about, as if the law of gravity 

 were a myth, existing only in the imagination of philosophers. 

 When the cloud was quite blown away by a more powerful air- 

 current, it in the course of a few seconds reformed. The contents 

 of each ascus could be seen to be separately ejected in a minute 

 jet consisting of a limited number of sporidia, which speedily 

 became lost with the others forming the cloud." From this 

 description it seems evident that the cloud of spores which forms 

 above a fruit-body of a Morchella is very similar to that which 

 forms under the pileus of a Hymenomycete, such as a Mushroom 

 or a Polyporus. In both clouds the spores are separated from 

 one another and fall so slowly through the air that they can 

 readily be carried off by very slight air- currents. 



1 R. Falck, " Die Sporenverbreitung bei den Basidiomyceten," Beitrage zur Biol. 

 der Pftanzen, Bd. IX., 1904, p. 51. 



2 C. B. Plowright, "On Spore Diffusion in the larger Elvellacei," Grevillea, 

 vol. ix., 1880-81, p. 47. 



