v] SPHAERIALES 163 



The family is rich in conidial forms, and it is probable that several species 

 ol Fungi tmperfecti, including the pyenidial genera Pkomaand Hendersonia 

 and also Cercospora, a form with long septate conidia on free conidiophores 

 are stages in the development of members of the Pleosporaceae. 



PLEOSPORACEAE: BIBLIOGRAPHY 



6 Woronin, M. Sphaeria Lemaneae, Sordaria fimiseda, Sordaria coprophila, und 



Arthrobotrys oligospora. Beit, zur Morph. und Phys. der Pilze, iii, p. 325. 

 1 Miyabe Kingo. On the Life History of Macrosporium parasiticum, Thiim. Ann. 

 Bot. iii, p. 1. 

 i] ; Brii rley,W. B. The Structure and LifeHistoryof Leptosphaeria Letnaneae (Cohn). 

 Mem. and Proc. Manchestei Lit. and Phil. Sue. Ivii, 2. p. 1. 



Gnomoniaceae 



The Gnomoniaceae are for the most part saprophytic on the leaves or 



1 1 



ther parts of plants. The perithecia are embedded in the substratum from 

 which their long necks project. The ascus is characterized by a thickened 

 apex through which a canal allows the exit of the spon-s. The spores are 

 hyaline and paraphyses arc usually not developed. The family differs from 

 the Pleosporaceae in the long neck of the perithecium and the thickened 

 apex of the ascus. There is no stroma, and this fact, as well as the dark 

 colour, distinguishes Gnontonia from the similar genus Polystigma among 

 the Hypocreales. 



Gnomonia erythrostoma is the cause of an epidemic disease known 

 as cherry-leaf-scorch, which attacks the foliage of Primus avium and of 

 several varieties of the cultivated sweet cherry. The mycelium ramifies on 

 the leaf and runs back to the base of the petiole, where it prevents the 

 formation of the absciss layer. In consequence the infected leaves do not 

 fall, but remain hanging on the branches; they are the only source of 

 infection in the following summer, and their destruction is therefore a sure 

 method of checking the disease. 



Infection usually takes place in June; towards the end of August spermo- 

 gonia appear; they are shallower than those of Polystigma, but otherwise 

 \ ery like them, with a wall of closely compacted hyphae and a small circular 

 1 1 1 ile opening on the under surface of the leaf. The spermatial hyphae are 

 narrow and tapering, and their extremities are abstricted to form the sper- 

 matia, each of which contains a long threadlike nucleus and a relatively small 

 amount of cytoplasm. 



Soon after the spermogonia have begun to develop certain hyphae near 

 the lower epidermis of the leaf become entwined to form more or less 

 spherical coils, the primordia of the ascocarps. Their apices project in 

 groups of tour or five through the stomata, and the terminal cells become 



