MORPHOLOGY AND LIFE HISTORY OF SOME ASCOMYCETES 437 
The conidiophores arise as simple branches which are pushed out through 
the stomata (text fig. i, a). Later branches arise from the basal cell of the 
older conidiophore within the stoma, often forming a fascicle of six or eight 
conidiophores of varying ages. The fascicle may often be scraped off and 
remain fastened together by this basal cell. 
Text Fig. i. Conidiophores and conidia of Sphaerella Bolleana from fig. leaf: a, 
section of lower portion of leaf with young conidiophores emerging through stomata; 
h, clump of old conidiophores; c, conidia, showing variations in size and shape, a, X 580; 
h and c, X 300, 
Artificial Cultures. On culture media the growth of the mycelium was 
also very slow. Cultures were obtained by planting the conidia on agar 
plates and then transferring the conidia, after germination, to plates of sterile 
agar or to various other media. The germ tubes branch very profusely, 
forming a small dense colony. The mycelium is at first colorless but after 
four or five days begins to darken and gradually changes to various shades 
of olive depending upon the nature of the substratum. 
On bean agar and on steamed green bean pods the colonies are small 
(usually less than a centimeter in diameter), circular in outline, and slightly 
raised. The base of the colony is slightly stromatic, and composed of 
black, thick-walled cells. This is covered with a velvety growth of gray 
to olive-brown hyphae. 
On steamed Irish potato plugs the growth is less vigorous than on bean 
pods; though otherwise it is very similar. Apparently the fungus is not 
able to assimilate the potato starch. 
Steamed sweet potato plugs gave the best growth of any medium tried. 
The growth was more rapid and the ultimate size of the colony much greater 
than on the other media. At the end of six weeks the colonies had, in 
most cases, practically covered the plugs which were one and a half centi- 
meters in diameter by about four centimeters in length. The colony was 
capitate, raised half a centimeter or more at the center. The base, next 
the substratum, was composed of large, black filaments which broke up 
easily into individual cells. The surface growth was composed of more 
slender hyphae light gray in color with a tinge of pink toward the center 
of the colony. 
