556 
ADRIAN J. PIETERS 
It will be noted that not so many sporangia were formed in the 
0.075 percent haemoglobin as in the 0.05 percent used in series I, 
and that the numbers of sporangia were nearly the same in all the 
dishes, so that any influence on the production of oogonia can be 
disregarded. This table shows, as did Table X, that there is no 
constant relation between the amount of dry weight a culture medium 
will produce and the number of oogonia formed by the mycelium after 
transfer. In only one case do these figures agree; the mycelium out 
of 0.1 percent peptone is at the bottom of the list in both instances. 
The greatest weight was made by mycelium out of i percent peptone 
which was seventh in the production of oogonia. Mycelium out of 
solution number 9 had the largest number of oogonia and was sixth in 
weight. The second heaviest mass of mycelium was out of solution 
number 11 and this was sixth in the production of oogonia. The 
results secured in the first experiment are therefore confirmed so far 
as concerns this point. The value of maltose is also confirmed, and 
the great difference between the value of dextrose and levulose in 
the conditions of this experiment is brought out. Dextrose added to 
peptone increased the weight of mycelium slightly, but the number 
of oogonia not at all, while the addition of levulose produced a my- 
celium with a tendency toward the production of oogonia quite out of 
proportion to its value for vegetative growth. 
In the course of this work many tests were made to determine the 
effect on the production of oogonia when salts or sugars were added 
to the haemoglobin. If it is true that levulose is an especially favor- 
able form of carbohydrate for the production of oogonia, this fact 
should also be brought out if levulose is added to haemoglobin. This 
was done in a number of cases and the results confirm the conclusion 
that for 5. ferax levulose has an especial value for the production of 
oogonia. 
In Table XIV the results of one test are brought together. 
Table XIV 
Saprolegnia ferax. Mycelium Out of Pea Extract in Haemoglobin and in 0.025 Per- 
cent Haemoglobin and sugars. In Every Case Concentration of Sugar Equals 
1/200 Molecular. Figures Represent the Number of Oogonia Formed in 
25 Sq. Mm. of Mycelium After Nine Days 
Haemoglobin Haemoglobin Haemoglobin Haemoglobin Haemoglobin Haemoglobin 
0.025^ o.osi + Dextrose + Levulose + Maltose + Sucrose 
21 34 49 129 14 92 
