193 
A. oryzae is a mould of a yellowish green color when seen in the ma- 
ture stage. The color varies with the age of the plant and also with the 
medium upon which the plant is grown. Favorable solid media are bran, 
rice, and wort gelatine. On rice and wort gelatine the young growths are 
of a light yellow green, the color being due to the numberless conidia 
formed. As the growth ages, the color changes to dark olive green. On 
plate cultures the mycelia are usually in colonies, due to the massing and 
germination of a number of conidia in one spot; as a result, the plate pre- 
sents a very irregular growth appearance (photograph 1). On bran the 
color of the young growth is much darker than that of the same age on 
rice, and in old growths the color is brownish olive to dark brown. In 
very old growths not a trace of green appears. 
The mycelium is a mass of fine, fleecy filaments, very much branched, 
and containing numerous septa. Wehmer states that the branching and 
septa were not easily seen, except with high magnification, but I had no 
difficulty in seeing both features with low powers, as photographs 2, 35 
will show. These were taken from gelatine-plate cultures. The magnifi- 
cation is 75 diameters. In young growths the filaments are filled with a 
finely granular protoplasm, which becomes much vacuolated as growth 
proceeds (photographs 4, 5). The filaments vary much in diameter even 
in the same culture, the main filament being large, while the branches 
taper, sometimes these being extremely fine. In old cultures the filaments 
become very large, thick and rough-walled (photograph 6). They are al- 
ways colorless. s 
The conidiophores can usually be distinguished from the mycelial 
hyphae as they gradually enlarge to the spherical end. The length varies 
to such an extent that any figures would not mean anything. The co- 
nidiophores are sometimes short branches at right angles to the filaments 
from which they arise sometimes so long that their connection is somewhat 
difficult to determine. Biisgen gives the length of the conidiophore as 
5 mm., Schroter, 1 mm., while Wehmer merely states that they vary in 
length. They become much enlarged in old cultures, the walls become 
very much thickened and roughened (photographs 8, 9). 
In young growths the sterigmata are short and regular, and vary from 
a few in number to sufficient to completely cover the spherical head; but 
in older growths, especially when submerged, they become _ septate, 
sometimes a sterigma developing into a conidiophore, which on its end 
13—Scrence. 
