96 
CHARLES THOM AND MARGARET B. CHURCH 
been called a Sterigmatocystis. That usage is disregarded in this 
paper. Comparative study of these two groups of races, A. fumigatus 
and A. nidulans, brings cumulative evidence of close relationship. 
Aspergillus rehmii Zukal and Sterigmatocystis sydowi Bainier and 
Sartory have both been cited as A. nidulans but this does not seem 
to be justified by examination of all the data given. Aspergillus 
flavo-viridescens Hanzawa appears to be more closely related to A. 
versicolor than to A. nidulans. S. glauca, S. minor, and S. prasina of 
Bainier and S. olivacea Van Tieghem might have been varieties of 
A. nidulans. The descriptions are inadequate for identification. 
Group Characterization of A. nidulans from Cultures. — Colonies on 
Czapek's solution agar, white to yellowish green, finally fairly deep 
green, velvety to more or less floccose in purely conidial areas, definitely 
floccose when perithecia are forming, reverse and agar usually more or 
less reddish to dark red or reddish brown, conidiophore more or less 
flexuous with the walls colored in shades of cinnamon brown, septate 
or unseptate, usually 50-100 fx but up to 200 long by about 3-5 
in diameter, increasing gradually to a dome-like vesicle 7-15 m in 
diameter, bearing sterigmata in two series, parallel with axis of the 
stalk; primary sterigmata varying, 5 by 3 to 7-8 fx by 2-3 ^u; second- 
ary sterigmata 7-10 fx by 2-2.5 Mi conidia globose up to 3 /x or 3.5 fx, 
occasionally to 4 in diameter, smooth or rough, greenish, in parallel 
chains adherent into a solid column 30-50 m in diameter and up to 
100-200 jjL in length. 
Perithecia becoming globose, up to 200-300 /x in diameter sur- 
rounded by floccose white to gray mycelium, the branches producing, 
either terminally or in a terminal series, yellowish to cinnamon globose 
cells up to 25 fx in diameter with walls 4-5 fx in thickness (the Hiille) ; 
perithecial walls thin, brittle, consisting of one or two layers of polyg- 
onal cells from pink to deep red, almost black, turning blue with the 
addition of alkali and red again with acid. Asci pink to purple, 
numerous, filling the perithecia, 8-spored; asci and ascospores varying 
in size with the race or species. The following variations may be de- 
scribed : 
I. A. nidulans Eidam. Asci 10. 5-1 1 ix, ripening slowly over a 
period of many weeks; ascospores slightly oval, about 5 by 4 /x, 
smooth with deep purple walls, separating into two valves in germi- 
nation. A culture with this type of ascospores has recently been 
found by us among the soil forms isolated by Waksman in New 
Jersey. 
