358 PLANT DISEASES 



hence the asci are naked, and almost free on the surface of 

 the host, i-4-8-spored, the asci frequently becoming crowded 

 with myriads of secondary spores produced by germina- 

 tion of the ascospores within the ascus ; paraphyses rare. 



Exoascus, Fuckel. Mycelium perennial in the host- 

 plant, in some species much reduced, and located between 

 the cuticle and the epidermis, in others more abundant, 

 intercellular in the tissues below the epidermis, and causing 

 malformations, as 'witches' brooms/ etc. Asci formed 

 in a series below the cuticle through which they emerge 

 to the surface at maturity, sometimes furnished with a 

 stem-cell which is cut off from the ascus by a septum ; 

 stem-cell or base of ascus usually penetrating between the 

 epidermal cells of the host. The asci at first contain 8 

 spores, but these often produce secondary spores of small 

 size which completely fill the ascus. 



Exoascus deformans, Fuckel, Symb. Myc., 1869, p. 252. 

 Asci cylindrical, apex rounded, 35-40X9-10 /*, stem-cell 

 6-8 X 6-9 /*, base somewhat pointed, and penetrating between 

 the epidermal cells. 



Exoascus pruni, Fuckel, Enum. Fung. Nassoviae^ 1861, 

 p. 29, fig. 26. The asci are 40-55x8-15 //,, stem-cell 

 10-16 /x, high, and about 5 //. broad at the base, which is 

 seated upon the epidermal cells, but not penetrating be- 

 tween them ; spores averaging 4-5 /x, diam. 



Exoascus cerasi, Sadeb., Jahrb. der Hamburgischen 

 Wissensch. Anstalten, x. 2, 48 (1893). Asci slender, clavate, 

 apex rounded, 30-50x7-10 //,, stem-cell 10-16x5-8 /*, 

 occasionally only about 3-5 p thick ; spores 6-9 X 5-7 /*. 



