702 
Journal of Agricultural Research voi. xxvn, no . 9 
% 
that the description which follows is sufficiently detailed to permit of 
identification by subsequent investigators, though lack of knowledge 
concerning the genus as a whole prevents one from knowing what char¬ 
acters should receive particular attention. 
Hyphae on the surface of apple leaves are normally scant or lacking, 
dark olive when present; but in moist chambers they are abundant and 
Fig. i.—A. Conidia of Alternaria malt as produced on apple leaves and above the surface in corn-meal 
agar cultures. B. Types of conidiophores including the so-called beaks or isthmi. C. Outline of a 
verrucose conidium. D. Conidia produced on the surface of the medium in corn-meal agar cultures. 
E. Conidia of form B produced at the surface of or in the culture medium. F. Conidia of form B 
with long so-called beaks or isthmi. A, B, D, E, and F X 3 2 S- C X 525- 
are light gray in mass with occasional darker areas. In corn-meal agar 
cultures the hyphae at or near the surface of the medium vary from 
nearly hyaline to dark olive, the latter predominating. On apple leaves 
their arrangement is usually fasciculate, but on artificial media they may 
lie parallel to one another and nearly in one plane, forming a sheet or 
layer. The hyphal segments are short, often no longer than their width, 
without constrictions at the septa. They are 3 to 8 // wide and seldom 
