RELATION BETWEEN VEGETATIVE VIGOR AND REPRODUCTION 555 
mycelium was transferred to haemoglobin; that this mycelium was 
then in good condition is shown by the large number of oogonia pro- 
duced. We may then conclude that invert sugar is an especially 
valuable food for the subsequent production of oogonia; that sucrose 
cannot be utilized by this fungus, but that maltose is used and is a 
good food both for vegetative growth and for the production of oogonia. 
(In series II the oogonia rarely developed oospores. This was due 
probably to contaminated haemoglobin. The entire set was dis- 
carded.) 
Series III. — This series was prepared to repeat the work in series I 
and also to determine if possible which of the two sugars present in 
sucrose, dextrose or levulose, was most used by the fungus. Solu- 
tions containing salts as well as sugars were also prepared and cultures 
grown in them, but since the large number of cultures thus set up 
would make it impracticable to handle all at one time those with 
salts were transferred in a separate lot. For some reason not deter- 
mined, all of the mycelia from the solutions containing salts failed to 
make oogonia or at most produced but a few oogonia each. Since 
this result was obviously due to some abnormal condition the entire 
lot was discarded and the results with the sugars alone are presented. 
Table XIII gives all the data for this series. 
Table XIII 
Series III. Saprolegnia ferax. Mycelium Out of Culture Media in Column Two. 
Grown Seven Days Before Transfer to 0.075 Percent Haemoglobin and Thirty 
Days in 200 cc. Liquid Before Weighing; Weights in Milligrams. 
Oogonia Count Recorded to Nearest Whole Number. Tem- 
perature i5°-i8° C. Sugars All 1/50 Molecular 
No. 
Food 
Weight 
Record After 2 Days 
Oogonia After 
Spo- 
rangia 
Oogonia 
3 Days 
17 Days 
I 
Pea 
0.041 
1 + 
II 
III 
46 
2 
Peptone 
0.1% 
0.0172 
O-I 
0 
Few 
21 
3 
0.2% 
0.0376 
I 
O-I 
I 
46 
4 
0.5% 
0.079 
II 
0 
O-I 
38 
5 
1% 
0.124 
II 
0 
I 
41 
6 
0.1% + sucrose 
0.024 
I-II 
0 
O-I 
29 
7 
0.068 
II 
0 
I 
65 
8 
0.1% + dextrose 
0.023 
II 
0 
O-I 
28 
9 
0.1% + levulose 
0.061 
I 
I 
II-III 
73 
10 
0.2% + sucrose 
0.0404 
II 
0 
I 
28 
II 
0.099 
II 
I 
II 
43 
12 
0.2% + dextrose. .... 
0.0474 
II 
0 
Few 
24 
13 
0.2% -|- levulose 
0.065 
II 
Starting 
O-I 
55 
20 
Haemoglobin 0.1% 
0.0199 
I-II 
0 
Few 
22 
