40 Briiisk Ftuigi. 



of extension^ suddenly becomes ruptured near tlie 

 apex ; at the same time the elastic lateral wall con- 

 tracts, and the spores are driven out through the open- 

 ing. In many species there is a definitely circum- 

 scribed apical portion of the ascus which is either 

 carried completely away or remains attached by one 

 side after dehiscence^ the spores passing through the 

 opeiiing formed. In many Ascomycetes, especially in 

 the group known as the Discomycete.^, the spores are 

 ejected in little clouds at intervals, due to the simul- 

 taneous dehiscence of numerous asci. This " puffing '^ 

 can be produced by shaking the fungus or by an 

 elevation of temperature. If a mature gill-bearing 

 fungus, as the common mushroom, is fixed with the 

 gills downwards about an inch above a sheet of 

 white paper, and allowed to remain for some hours, 

 the spores will fall, and it will be seen that they have 

 spread on the 2:)aper for some distance beyond the 

 radius of the pileus, showing that they have been 

 ejected by some means, and that this dispersion is not 

 due to a disturbance of the atmosphere, can be proved 

 by ]3lacing a bell-jar over the fungus. According to 

 Fayod,^ when the spores are mature, water accumu- 

 lates in the sterigmata, w'hich causes a sudden expan- 

 sion of the septum at the apex, and the spores are 

 jerked off. In the group including the puffballs, 

 Lycoperclonj and the earth-stars, Geaster, there is a 

 dense mass of differentiated hyphse forming the 

 ccqrillitiumj which assist by their elasticity in dis- 

 persing the spores, while in the Phalloidese, illus- 



* Histoire Xaturelle des Agaricines. Ann, Sci. Nat., ser. vii., 

 vcl. ix., p. 181. 



