CHEMICAL STIMULATION OF GROWTH OF ASPERGILLUS NIGER 34I 
In all except 10 : o.oi : 2.5 (NH4NO3 : KH2PO4 : MgS04. 7H2O), good sporulation was 
obtained; in the latter slightly less sporulation and no membrane, but the solution was full 
of submerged hyphae, apparently in a solid mass. 
II. The effect of a variation in concentration of the ammonium nitrate in the Pfeffer 
solution. 
25 :5 :2.5* 
15 : 5 :2-5 
0.1 :5 : 2.5 
0.01 : 5 : 2.5 
0.430 g. 
0.409 g. 
0.070 g. 
0.023 g. 
0.346 
0.372 
0.058 
0.022 
0.403 
0.329 
0.060 
0.029 
0.368 
0.324 
0.057 
0.030 
0.331 
0.363 
0.061 
0.042 
0.376 
0.359 
0.061 
0.029 
NH4NO3 
KH2P04 
MgS04. ■ 
25 
: 5 
: 2.5 
15 
: 5 
: 2.5 
O.I 
: 5 
: 2.5 
O.OI 
: 5 
: 2.5 
Sporulation 
Good. 
Sparse, solid mass submerged hyphae and membrane. 
Very sparse, solid mass submerged hyphae and membrane. 
* MgS04.7H20 (Kahlbaum). 
12. The effect of a variation in concentration of the magnesium sulphate in the Pfeffer 
solution. 
10 : 5 : 25 
10 :5 : 10 
ID : 5 : 0.1 
10 : 5 : 0.01 
0.552 g. 
0.360 g. 
0.156 g. 
0.087 g. 
0.450 
0.353 
0.127 
0.087 
0.487 
0.387 
0.178 
O.II2 
0.540 
0.372 
0.182 
0.I2I 
0.488 
0.371 
0.284 
O.II8 
0.503 
0.369 
0.185 
0.105 
Sporulation in all except 10 : 5 : o.oi, good; in latter, fair. 
In experiments 10, 11, and 12 we find that if we vary the concentration 
of ammonium nitrate, of monopotassium phosphate, or of magnesium sul- 
phate in the Pfeffer solution, the others being held constant, the effect of a 
decreased concentration is a decreased yield, that of an increased con- 
centration an increased yield. 
13. The effect of an increase 'n concentration of the monopotassium phosphate in the 
Pfeffer solution. 
Strain W, 5 
Control KH2PO4 Yield 
0.133 g. 10 : 29 : 2.5 0.153 g. 
0.124 10 : 45 : 2.5 0.246 
0.146 10 : 65 : 2.5 0.190 
0.140 10 : 85 : 2.5 0.381 
0.121 10 : 105 : 2.5 0.369 
0.133 
% 
