130 Keport of the Depaktment of Botany of the 



fruit and canes. The spores are formed in pustules, technically 

 known as acervuli, which originate underneath the epidermis of 

 the leaf, chiefly on the upper surface. The epidermis becomes 

 blackened and elevated so as to form a small pimple. At matur- 

 ity this pimple is ruptured at the summit and the spores escape 

 in a gelatinous mass which appears as a whitish or flesh colored 

 speck at the center of the spot. The spores, which are one-celled 

 and uncolored, are somewhat variable as to size and shape. 

 Usually they are strongly curved and somewhat larger at one 

 end. (See Plate 1, Fig. 2.) As we have found them, the spores 

 measure 12 to 24, a in length by 5 to 9 ja in width, the most com- 

 mon size being 19 by 7/^. 



In our exjierience there has never been any difiijculty to find 

 the spores in abundance on the affected leaves. They are also 

 fairly abundant on the new canes and on the petioles. On the 

 canes they are much more easily found while the canes are fresh. 

 Upon drying, the contrast of color distinguishing the acervuli 

 largely disappears. From dried specimens of the canes the 

 spores are most easily obtained by scraping the bark after a 

 brief immersion in water. On the fruit stems and berries the 

 spores are found less frequently. 



So far as known, Glccosporium ribis has but the one spore form 

 above described. However, it is quite possible that there exists, 

 also, an ascigerous form in which the fungus passes the winter. 

 Fuckel^ has suggested such a relationship with Sphcoria circinata 

 Fckl. [=Onomaniella circinata (Fckl.) Sacc] 



By means of artificial cultures Miss Stoneman^ has shown that 

 two other species of Glceosporium, G. cingulatum Atk. and G. 

 viperatum E. & E., have in their life cycle ascigerous forms 

 referable to a pyrenomycetous genus for which she proposes 

 the name Gnommiiopsis. 



Excellent figures of Glwosporium rihis are found in Briosi & 

 Cavara's Funghi parassiti delle piante coUivate od utili, Fasc IX, 

 Nr. 222. 



'Fuckel. L, Symbola Mycologieie, p. 111. 



'Stoueman. Bertha. A Comparative Study of the Development of some 

 Anthracnoses. Botanical Gazette, 26:101-100. 



