Ii6 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
may be altered by a change in the medium, while those of other structures 
may remain constant as long as the medium is not totally inadequate or 
does not contain deleterious substances. Aborted or unrecognizable types 
of structure result from conditions positively inhibitive for normal growth. 
Conidial growth, sclerotia, or perithecia, each may be totally or in part 
suppressed or their production may be stimulated by the nutrient provided. 
The structure and markings of the stalk wall, general shape, markings, 
and range of size in conidia are fairly stable within the strain or species and 
fall within certain limits which for practical purposes do not vary. The 
length of the stalk, diameter of the vesicle, the dimensions of the primary 
sterigmata, and, within limits, the spore measurements are influenced by 
the substratum. Wall markings cannot be said to vary with the nutrient 
supplied, although their conspicuousness varies slightly from culture to 
culture doubtless through the pressure of several factors. The alterations 
in these latter structures are never permanent. They are dependent entirely 
on the substratum. Certain media stimulate in such fashion as to cause 
an increase in dimensions, others a dwarfing. The majority of culture 
media cause each strain to develop to a size falling within fairly well-defined 
limits. 
Aspergillus Wentii and Related Forms 
Aspergillus Wentii was described by Wehmer*^ and has been widely 
distributed in culture from the Centralstelle at Amsterdam. Extensive 
cultural studies show the species to differ from the characterization given 
by Wehmer in the quite general presence of both primary and secondary 
sterigmata. Identity of the Amsterdam strain with Wehmer's material 
is hardly questionable. Cultures with the same morphology have been 
found by us upon moldy corn grains, upon moldy cotton cake from Georgia, 
(4230) within a temechee nut from Brazil, upon cubebs from Singapore, 
and received (4204.16c) from China through the kindness of Mr. Chung, 
from Hanzawa (4291.32) in Sapporo, (4186.34) from Panama collected 
by Dr. Thaxter, from Oregon soil (4078.0-5) collected by Waksman. One 
culture was received from Ohio Experiment Station, one from Prof. R. A. 
Harper. Although these forms differ in details of reaction and appearance, 
the morphological characters found mark them as a natural group. 
Characterization of A . Wentii Wehmer. Colonies on Czapek's solution 
agar with cane sugar, deeply floccose, spreading, with sterile hyphae white 
or yellowish, and with heads white at first, changing through cream, cream 
buff, honey yellozv, old gold, to light brownish olive, medal bronze, or in old cul~ 
tures sometimes snuff brown (Ridgway, column 19, Plates IV, XVI, XXX, 
and Plate XXIX 15'' K; recorded as coffee-brown to chocolate brown by 
Wehmer), and in some strains producing large masses of aerial mycelium 
which in tubes may fill the lumen 3 cm. above the substratum; reverse of 
colony yellowish at first, becoming reddish brown when old; agar frequently 
Wehmer, C. Eine neue technische Pilzart Javas. Centralbl, Bakt. II, i : 150. 1895. 
