132 FUNGI. 



observed for a time a whitish cloud will be seen to rise suddenly 

 from the surface of the disc, which is repeated again and again 

 whenever the specimen is moved. This cloud consists of 

 sporidia ejected simultaneously from several asci. Sometimes 

 the ejected sporidia lie like frost on the surface of the disc. 

 Theories have been devised to account for this sudden extrusion 

 of the sporidia, in Ascobolus, and a few species of Peziza, 

 of the asci also, the most feasible one being the successive 

 growth of the asci ; contraction of the cup may also assist, as 

 well as some other less potent causes. It may be remarked 

 here that the sporidia in Peziza and Helotium are mostly colour- 

 less, whilst in Ascobohis they pass through pink to violet, or 

 dark brown, and the epispore, which is of a waxy nature, be- 

 comes fissured in a more or less reticulated manner. 



The sporidia in Hi/sterium proper are usually coloured, often 

 multiseptate, sometimes fenestrate, and occasionally of consider- 

 able size. There is no evidence that the sporidia are ever 

 excluded in the same manner as in Peziza^ 

 the lips closing over the disc so much as to 

 prevent this. The diffusion of the sporidia 

 probably depends on the dissolution of the 

 asci, and hence they will not be widely 

 dispersed, unless, perhaps, by the action of 

 rain. 



In Tympanis, asci of two kinds have been 

 observed in some species ; one kind contain- 

 ing an indefinite number of very minute 

 bodies resembling spermatia, and the other 

 . octosporous, containing sporidia of the usual 

 type. 



The Sph&riacei include an almost infinite variety in the form 

 and character of the sporidia. Some of these are indefinite in 

 the number contained in an ascus, although the majority are 

 eight, and a few less. In the genera Torrubia and Hypocrea the 

 structure differs somewhat from other groups, inasmuch as in 

 the former the long thread-like sporidia break up into short 

 joints, and in the latter the ascus contains sixteen subglobose or 



