Mar., 1921] HAENSELER — GROWTH OF ASPERGILLUS NIGER* 
gave a yield of 0.328 gram. The average yield from the C2 cultures of 
series 2 is 0.333 gram, and from the Ci cultures of series 3 it is 0.348 gram. 
This agreement is extremely close when it is considered that the partial 
concentrations due to either KH2PO4 or MgS04 in these cultures vary 
from less than o.i atmosphere in series i to more than 3.0 atmospheres in 
series 3. A similar equality between dry-weight yields exists for all the 
cultures containing equal quantities of NO3 in the group comprising series 
I, 2, and 3. This same relation exists also in the group comprising series 4 
and 5. The direction of the graph of each series with a given total salt 
concentration indicates an approximately linear relation between the dry- 
weight yields of the fungus and the proportions of NO3 in the media. 
Gms. 
1.00 
.90 
.80 
. 70 
. 60 
.50 
.40 
.30 
.20 
.10 
\ 
Ser. L 
Ser. 2 
Ser. 3 
Ser, 4 
Ser. 5 
Gms.NO^ 
per Liter 1 2 3 4 5 6 
Fig. 5. Graph showing relation between dry- weight yields of Aspergillus niger and the 
NO3 content of the nutrient solution. 
It will be observed that the graphs of series 3 and 5 (fig. 5) break abruptly 
at the point where high yields are indicated. This sudden break itself, 
according to Blackman (i), indicates that a limiting factor for growth had 
entered at this point, and, as already pointed out, this is attributed to the 
exhaustion of the sugar content in these high-yielding cultures. 
That growth in the two series in question was limited by the amount 
of sugar available in the cultures is clearly brought out in a series of eight 
duplicate cultures in which the sugar content was made to vary from a 
calculated osmotic concentration value of i.o atmosphere to one of 8.0 
atmospheres, by increments of one atmosphere, the total salt concentration 
and the salt proportions remaining constant in all the cultures. The 
