Feb., 1921] 
THOM AND CHURCH — ASPERGILLUS 
105 
The forms reported here have each been restudied several times, some of 
them at intervals of several years, to determine which characters were 
variable with conditions of culture and which were stable. 
The following cultural descriptions of A.flavus, A. oryzae, A. parasiticus, 
and A. effusus are prepared as typical for races or groups of nearly related 
strains, which represent fairly widely separated portions of the whole series. 
Characterization of A. fiavus Link.^ Colonies on Czapek's solution 
agar with sucrose, spreading widely, with floccosity limited to scanty growth 
of a few aerial hyphae in older and dryer areas among the erect crowded 
conidiophores ; sclerotia at first white, then brown, hard, parenchymatous, 
in a few strains white-tipped, produced abundantly by some strains, scantily 
by others under undefined conditions, not or rarely by still others ; perithecia 
not found. Conidial areas ranging in color in different races from sea-foam 
yellow through chartreuse yellozv, citron green or lime green, to mignonette 
green, Kronberg's green, or more rarely to ivy green (see Ridgway XXXI. 
25'' f,d,b,i,k,m;7 approximately C. D. C. 270, 271, 266, 252, 253, 257),^ 
persistent or changing in very old colonies toward Isabella color to brownish 
olive (Ridgway XXX. 19'' l,m), zinc orange (Ridgway XV. 13'), or even 
Saccardo's umber (Ridgway XXIX. 17'' k) ; reverse (or under side) and agar 
either uncolored or more or less intensely yellowed, from pinkish buff, 
cinnamon buff, to clay or even Saccardo's umber (Ridgway XXIX. 17" 
d, b, to k), or in some cases even darker brown in old and dry cultures. 
Stalks arising separately from substratum, 400 to 700 ijl ,even to 1000 fx 
long, 5 to 15 jLt in diameter, broadening upward, with walls colorless, so pitted 
as to appear rough or spiny with low magnification, occasionally granuli- 
ferous, varying in thickness, gradually enlarging to form a vesicle 10 to 30 
or even 40 fx in diameter. Heads in every colony varying from small with a 
few chains of conidia to very large stellate or columnar masses, or both 
mixed in the same area (fig. i, c and d); small heads with small dome-like 
vesicles and a single series of a few sterigmata up to 10 to 15 ju by 3 to 5 ^i; 
larger heads partly with simple sterigmata, partly with branched or double 
series, or with both in the same head; primary sterigmata 7 to 10 by 3 to 
4 m; secondary series 7 to 10 /x by 2.5 to 3.5 //; conidia pyriform to almost 
globose, from almost colorless to yellow-green, with walls so thickened as to 
leave circular, elongated, or winding pits, giving a rough or echinulate 
effect^ when viewed with low magnification, varying in size in different 
strains and even in the same culture, frequently 2 by 3 )U, 3 by 4 ju, 4 by 5 m> 
or 5 by 6 /X in diameter, or even larger in some strains. 
Colonies grow best in starch- and sugar-containing media; some strains 
fruit at temperatures up to 50° C. Spores survived heating^*^ to 57.2° C. 
for 30 minutes and dry heat at 110° C. for 30 minutes. 
This description was originally based upon culture no. 108 received 
from Amsterdam and identical with no. 3526 obtained directly from Wehmer. 
^ This characterization is revised and extended from the form furnished to Dr. John R. 
Johnston and pubhshed by him (loc. cit.). 
^ Ridgway, R. Color standards and color nomenclature. Washington, D. C, 1912. 
^ Klincksieck, P., and Valette, T. Code de couleurs. Paris, 1908. 
3 "Areolate" of Johnston. 
^°Thom, C, and Ayers, S. H. Jour. Agr. Res. 6: 153. 1916. 
