HELIOTROPISM OF ASCI IN DISCOMYCETES 285 



end of the ascus becomes straighter, and then the opercuhim can 

 be seen occupying a more or less obUque position at the end of the 

 ascus (Fig. 135, / /). Investigation of fruit-bodies of C. scuieUata 

 grown under various conditions of hght seems to indicate that the 

 opercuhim really originates symmetrically at the end of the ascus, 

 but that, owing to heliotropic curvature of the end of the ascus, 

 the operculum becomes pushed to one side — the side which is 

 nearest to the source of light. Thus the more or less oblique 

 position of the mouth of the ascus of Ciliaria scutellafa and of other 

 similar Discomycetes is not a purely " morphological character " 

 as Seaver ^ thought, but is a physiological character caused by the 

 response of the ascus to the heliotropic stimulus of light. 



The Heliotropism of the Asci of Melastiza miniata and Cheily- 

 menia vinacea. — Fruit-bodies of these species came up in the 

 ice-house on pieces of planks and on sawdust along with those of 

 Ciliaria scutellata which they resemble in their flattened discoid form. 2 



The fruit-body of Melastiza miniata (Fuck.) Boud.=^ is an orange- 

 red disc which varies in large specimens from 1 to 2 cm. in diameter. 

 It is covered on its outer side by short blunt yellowish-brown hairs. 

 Its paraphyses are club-shaped at their ends. With iodine the 

 paraphyses turn green ^ but the asci do not turn blue. The spores 

 are oval-elhptic, colourless, verrucose, and often blunt at the ends. 



The fruit-body of Cheilymenia vinacea (Rabenh.) Bond, is a 

 yellow disc, 0- 5-1 • cm. in diameter (Fig. 136, A and C). It bears 

 on its outer side numerous long pointed septate hairs or setae (B). 

 Its paraphyses are cylindrical and not swollen at their free ends (F). 

 With iodine the asci do not turn blue. The spores are elliptic- 

 oblong, colourless, smooth, devoid of oil-drops, and about 20 [x long.^ 



1 F. J. Seavor, vide supra, pp. 255-2.57. 



2 The identification of Melastiza miniata and Cheilymenia vinacea wa.s made 

 with the help of the excellent descriptions and illustrations given by Boudier in 

 his Icones Mycologicae. 



3 According to Seaver {The North American Cup-fmigi, New York, 1928, p. 103), 

 this is a synonym for Melastiza Chateri (W. G. Smith) Boud. 



4 Boudier {Icones Mycologicae, T. IV. p. 218), by inadvertence, states that the 

 paraphyses do not turn green with iodine, but he correctly illustrates them as 

 turning green in his Plate C'CCLXXXVI. 



•'' The asci of Cheilymenia vinacea are described by Boudier as 270 \x long. In my 

 specimens they were only 230 \i long. 



