358 PLANT DISEASES 



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

 the host, 1-4-8-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, Symh. Myc, 1869, p. 252. 

 — Asci cylindrical, apex rounded, 35-40X9-10 i^, stem-cell 

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

 the epidermal cells. 



Exoascus pruni, Fuckel, Emini. Fung. Nassoviae., 1861, 

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

 10-16 /x high, and about 5 /x 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., JaJub. der Haviburgischen 

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

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

 occasionally only about 3-5 /x thick ; spores 6-9X5-7 l^- 



