STEINBERG: GROWTH OF ASPERGILLUS NIGER il 
The membranes were thick and wrinkled, opaque, and white to 
light tan in color. Spores were present only in small amount. 
The third generation cultures on this composition (7W3 and 7Y3) 
were used for the inoculation of bread cultures and these in turn 
for the inoculation of the cultures on the Pfeffer nutrient solution 
according to the usual procedure. The average yields obtained 
were (Exp. XV): | 
Culture Yield 
WN Di ae Oe SO ee o ee encima a 0.157 gram 
Wee as a es 4 Mine Sleunes pra te 0.232 
FN Beye tee A hte mee eae ee ae 0.147 
PM aati Pay ooo i Cie ee aa bop te ane he iene 02262): 
Apparently, no modification of the two strains had occurred by 
culturing on this agar composition for three generations, in so far 
as the yield obtained in the Pfeffer solution to which no zinc has 
been added is concerned. 
An additional experiment gave similar results (Exp. XVII): 


0.6. Mig. ZA: | 0.130 gram NO me Pus. | 0.187 gram 
i O.A58 0.01 i G:208) 



00 me. 201 | 0.109 gram | OO map Pay 55. 0.175 gram 
0.01 reneee| O00! 2: | 0.01 iy rae aaa EU 48 ag 

The results obtained by culturing in a similar manner on an- 
other medium led to apparently the same conclusion. The med- 
ium in this case consisted of I per cent. each of peptone, sucrose 
and agar. To this were added the salts (already tested by being 
used in the preparation of zinc-free Pfeffer solution) in the same 
amounts per liter as in the Pfeffer solution (p. 10). The cultures 
on this agar were similar in appearance to those on the zinc-free 
Pfeffer solution, agreeing in this respect with the peptone-sucrose 
agar cultures. A series of subcultures (8W and 8Y) were kept for 
three generations on the above medium (— 8W, — 8Y) and an- 
other series on the same medium to which 10 mg. Zn/L had been 
added (+ 8W, + 8Y). The results obtained on using this mater- 
ial for producing cultures on the liquid Pfeffer medium, to which 
no zinc was added (Exp. XVI), follow: 
