334 Bulletin 73. 



these dimensions, the asci being 25-45 long by 6-8 in diameter, 

 and the stalk cells 15-25 long by 3-6 in diameter. They are 

 somewhat pointed below and according to my observations do, to 

 a slight extent, project between the cells of the epidermis, but 

 not markedly so- The spores are rounded or oval in form and 

 are 3-4 in diameter. 



Prunus nigra Aiton. Wild Red Plum. 

 Exoasciis communis Sadebeck. 



Fruits of this plum distorted into the usual "pockets" or 

 "bladders," collected by C. H. Davis, at Alma, Mich., June 2, 

 1894, w^ere communicated to me by Prof. L,. H. Bailey. The fun- 

 gus agrees with Sadebeck's E. communis. The asci measure ^35 

 -45 long by 7-9 in diameter, and the stalk cells 15-22 high by 

 4-6 in diameter. The stalk cells are frequently pointed below 

 and occasionally intrude slightly between the epidermal cells as 

 in E. communis on P. maritima. The structure of the fungus 

 and the relation of the stalk cells to the epidermis is represented 

 in fig. 60. 



Prunus pumila L,. Dwarf cherry, 

 Exoascus commtmis Sadebeck. 



Exoascus communis is also described by Sadebeck on the dwarf 

 cherry, Pi'unus pumila ly. Mature conditions of the fungus on 

 this plum I have not seen. The plum "bladders" were formed 

 on the fruit of this species on some plants which are growing in 

 the Horticultural grounds of Cornell University, in June, 1894. 

 A photograph showing the form of these "bladders" and the nor- 

 mal fruit is represented in fig. 19. The surface of the swollen 

 fruits is quite uneven, and the tissue is characteristic of similar 

 tissues in other species of plums thus affected. These specimens 

 unfortunately did not mature their asci. 



Prunus angustifolia Marshall. Chickasaw plum. 



Exoascus mirabilis n. sp. 



This remarkable species deforms the leaf buds and young 

 twigs of Prumis angustifolia Marshall, the Chickasaw plum {P. 

 chicasa Michz.). It also occurs on related species of P^-unus. I 

 observed it in the vicinity of Columbia, S. C, in May, 1889, and 



