no 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
sclerotia nor perithecia were found. Colonies grew well in all common 
media, grew better at 37° C. than at 20° C, liquefied plain gelatine (gelatine 
in distilled water) with yellow color in the liquid. 
The puzzling appearance of these cultures led to studies in morphology 
and to extensive experiments scattered over nearly ten years. Comparative 
study of all species obtainable shows that the stalk throughout the genus 
Aspergillus originates as a mycelial cell transformed into a spore-producing 
organ. The cell enlarges in diameter and its wall becomes thickened. 
The stalk arises as a branch approximately perpendicular to the course of 
the original cell which remains in the hypha as a kind of foot. Usually 
the stalk, beginning with the diameter of its foot cell, broadens upward 
and lengthens, hence becomes many times the size of its foot. In A. effusus 
the foot cell is frequently very long, branching and connected with other 
foot cells to form a trailing, fertile hypha from which the stalks arise as 
short branches. Selective transfers from Lutman's strain (no. 130) showed 
the possibility of separating a race which appeared to be the usual form of 
A. flavus and another in w^hich the heads were borne only on the trailing 
type of fertile hyphae among cottony white masses of sterile hyphae. The 
hypotheses of symbiosis and of parasitism were both tested through many 
transfers without result. The heads on all series of cultures maintained the 
essential morphology of A. flavus, although the colony characters diverged 
widely. More recently, a transfer was made from a stock culture several 
months old which was grown upon Czapek's solution with the addition of 
5 percent sodium chloride, 10 percent sucrose, and 3 percent agar. The 
original strain (Lee 108) had maintained the cultural appearance oi A. flavus 
as received from Wehmer, through successive transfers for about four 
years. This transfer produced a floccose type of colony with some A . flavus 
type of fruiting at the edges. Transfer from the whitest areas in this 
culture produced the typical white colony described above; transfer from 
an area showing few small heads produced a mixed colony; transfer from 
selected heads appearing to be A. flavus gave a pure A. flavus colony. All 
of the experimental work supports the hypothesis that the floccose types 
represent mutants from the typicdiX A . flavus , which were probably induced 
in the last experiment in similar manner to the mutations of A. niger as 
described by Schiemann.^^ 
The description given by Tiraboschi {loc. cit.) for A. effusus probably 
applies to these cultures. A . effusus was isolated by Tiraboschi from spoiled 
corn products. 
Nomenclature. Aspergillus flavus was first described by Link^^ in 
Schiemann, E. Mutationen bei Aspergillus niger van Tieghem. Zeitschr. Indukt. 
Abstam.- u. Vererbungslehre 8: 1-35. 1912. 
2* Link, H. F. Observations in: Ordines plantarum naturales. Gesellschaft Natur- 
forschender Freunde zu Berlin, Magazin 3, p. 16. 1809. This is usually cited Link. Obs. 
p. 16. 1809. The description in full follows: "Caespitibus laxis, floccis albis erectis, 
capitulis junioribus albis, adultioribus fiavis. Frequens in plantis siccis herbariorum." 
