248 



RESEAKCHES ON FUNGI 



Comparison of the Sizes of Wind-borne Spores in Asco- 

 mycetes and Hymenomycetes. — The size of wind-borne spores, 

 which is so important a factor in determinin^f their rate of fall, 

 is doubtless adapted to the spread of the spores by such air- 

 cuiTents as ordinarily occur above the surface of the ground. 

 In this connection it is a distinctly interesting fact that although 

 Ascomycetes produce and then liberate their spores into the air 

 in a very different manner to that of Hymenomycetes, yet in 

 both groups of fiingi the order of magnitude of the wind-borne 

 spores is the same. Evidence supporting this statement is given 

 in the following Table, where the sizes of the spores of a few 

 Ascomycetes which make use of the wind for dissemination 

 are compared with the sizes of the spores of a few well-known 

 Hymenomycetes. In each series the spores are arranged accord- 

 ing to the magnitude of their short diameters. This arrange- 

 ment has been adopted because the rate of fall of spores, and 

 therefore the ease with which they can be transported by air- 

 currents, is chiefly determined by the size of their short diameters 

 and not by that of their long diameters, since spores tend to fall 

 with their long axes in a horizontal position.^ The unit of measure- 

 ment is 1 /x. The sizes of the spores of the Ascomycetes are those 

 given by Massee.- The sizes of the spores of the Hymenomycetes 

 were measured by myself and are taken from the Table in Part I., 

 Chapter XIV. 



Compariaon of the Sizes of Sjiores. 



Ascomycetes. 



Species. 



Bulgaria polymorpha 



Peziza aurantia 

 Gyromitra esculenta 



Morchella gigas 



Sliort 

 Axis. 



5-6 



7-8 

 9-11 



Long 

 Axis. 



Hymeuoiriy cotes. 



Species. 



i ( Polypoius scjuamosus . 



10-14 . Psallinta canipestris . 



I Marasinius oreades 

 1 '■-ic 5 Coprinus comatus 

 { Russnla enietica . 

 \1~-17) Ainaiiitopsis vagiiiata, 

 fniit-bixlv I. 



11-14 21-24 



Amaiiitopsis vaginata, 

 fruit-body III. 



I.ony 

 Axis. 



14-(i 

 7-2 

 9-5 



12-6 



8-8 

 l()-2 



11 



^ Of. the end of Chap. XV., Part I. 



G. Massee, British Fungua Flora, vol. iv. 



