248 ASCOMYCETES. 



A longitudinal section through a cushion exhibits a thick 

 hypothecium, consisting of a close pseudoparenchyma of hyaline 

 fungal cells, which permeate every tissue of the bark and cause 

 death of the cambium ; above this comes a looser layer with 

 many air-spaces, and over this the layer from which the asci 

 and paraphyses arise. 



The asci contain eight oval unicellular spores with distinct 

 cell-nuclei. When a section is placed in water, a very 

 evident swelling takes place, and the asci elongate to twice 

 their original length. I have not observed ejaculation of 

 spores, but rupture of the asci occurs in water-preparations 

 and the spores are set free in large numbers. The spores 

 probably germinate and infect young shoots, the mycelium 

 hibernating there. 



The effects of this fungus are death of diseased twigs of 

 willow above the spot where a sporogenous cushion is 

 formed. 



This species is also said to frequent Gorrnis in America. 



Cryptomyces pteridis (Rebent.) occurs on fronds of Pteris 

 aquilina, but whether a parasite or not is as yet uninvestigated. 

 The asci ripen after the fronds have passed through the winter. 

 To this belongs the conidial form Fusidium pteridis Eabh. 



Olithris. 



The apothecia, at first spherical, become oblong, and break 

 through the superincumbent layers by a lobed fissure. The 

 apothecial disc is oblong and flat. The club-shaped asci contain 

 eight hyaline spindle-shaped or thread-like spores, with one or 

 more cells. The paraphyses are thread-like. The majority of 

 this group are saprophytes. 



Clithris (Colpoma) quercina (Pers.) (Britain). According to 

 Schroeter,^ this causes disease and death of living branches of 

 oak. The oblong apothecial discs are greyish-white, and covered 

 at first by a brownish-grey wall which, later, becomes ruptured. 

 The ascospores are simple. Cylindrical pycnidia, with somewhat 

 bent conidia, are also produced. 



CI. juniperi (Karst.) occurs on living twigs of juniper. Nothing is 

 known of its parasitism. 



1 Schroeter, Pike Schlesiens, 1893. 



