466 RESEARCHES ON FUNGI 



of puffing are due to the spores and sap-drops bombarding the air and 

 setting it in motion mechanically and are not due to the fruit-body being 

 hotter than the surrounding air and sending out blasts of warm air. 



In Ascobolus magnificus about one-third of each ripe ascus protrudes 

 freely into air above the hymenium. This terminal part of the ascus 

 contains the eight spores and, when young, it executes a heliotropic 

 curvature toward the source of light. The paraphyses of A. magnificus 

 are an heliotropic. 



On the basis of Corner's work and investigations by the author, the 

 development and the structure of the apothecium of Ascobolus sterco- 

 rarius have been described and illustrated. The asci of this species do 

 not protrude so freely into the air as those of A. magnificus ; but, as 

 usual in the Ascoboleae, they are heliotropic. 



Our present knowledge of the apothecium of Ciliaria sculellata 

 (= Lachnea scutellata) has been summarised. 



The apothecium of Ciliaria scutellata is discoid and its hymenium is 

 flat or almost so. When an apothecium of C. scutellata develops in 

 unilateral hght, the asci all across the disc bend their free apical ends 

 in the direction of the source of light ; and, when puffing takes place, the 

 spores are all discharged toward the source of light. 



In respect to the heliotropism of their asci, the discoid fruit-bodies 

 of Melastiza miniata and of Cheilymenia vinacea resemble those of Ciliaria 

 scutellata. In all these three species, when an ascus which is curved at 

 its end discharges its spores, it straightens considerably and the oper- 

 culum, which was terminal, comes to occupy a more or less oblique position 

 on that side of the ascus which is nearest to the source of light. 



The fruit-bodies of Aleuria vesiculosa have been described and their 

 varieties discussed. Previous observations on the discharge of the spores 

 have been summarised. 



In a hemispherical apothecium of Aleuria vesiculosa the asci are 

 heliotropic, in consequence of which their free ends are all directed toward 

 the apothecium's mouth. Hence, when puffing takes place, the spores 

 are all shot out of the mouth of the apothecium and so escape freely into 

 the air. The outer halves of the asci on the sides of an apothecium may 

 be bent through an angle of 45°. The asci in the middle of the base of 

 the apothecium may be quite straight. The amount of bending of an 

 ascus varies with the position of the ascus in the hymenium and therefore 

 with the angle at which the light strikes the end of the ascus as it is 

 developing. 



The paraphyses of Aleuria vesiculosa attain maturity before the asci 

 and, Hke the asci, they are positively heliotropic. They bend toward 

 the source of hght and so point toward the mouth of the apothecium. 

 This arrangement assists the asci in pushing their way up between the 

 paraphyses as they develop. 



Observations made by H. T. Giissow in a wood in Ontario, Canada, 



