RELATION BETWEEN VEGETATIVE VIGOR AND REPRODUCTION 567 
These conclusions will be briefly discussed under the following 
heads. 
1. The relation between the weight of mycelium and the number of 
oogonia produced. 
2. The expression in one environment of tendencies acquired in a 
former environment. 
3. The value of levulose. 
4. The value of sucrose. 
5. The value of phosphates. 
The Relation between Weight of Mycelium and the Number of Oogonia 
Produced 
The question which was stated at the beginning of the paper, 
whether any constant and necessary relation exists between the 
vegetative growth and the reproductive activity in several species of 
the Saprolegniaceae must be answered in the negative. The record 
of experiments with Achlya racemosa, A. prolifera, Saprolegnia ferax 
and S. monoica all agree in showing that a mycelium out of a relatively 
poor solution, measured by vegetative growth, may produce more 
or larger oogonia than are produced on a mycelium from a solution 
that is much better for vegetative growth. This has, of course, 
nothing to do with the well-known fact that after a mycelium has been 
transferred to a new solution, vegetative growth may prevent the 
formation of oogonia. When a mycelium of 5. ferax is taken from pea 
extract and placed in a haemoglobin solution that is stronger than 
0.1 percent, few if any oogonia are produced; vegetative growth is 
excessive and prevents reproduction. Strong vegetative growth and 
reproduction cannot go on at the same time in the same solution but 
the problem under discussion is the relation between vegetative growth 
in one solution and reproduction by such a mycelium when transferred 
to another solution. It might be expected, a priori, that if a vigorous 
mycelium will produce a given number of oogonia when transferred 
to a suitable medium a more vigorous one, that is, one that had made 
a greater weight of dry matter in a given time in a fixed quantity of 
solution, would produce a greater number of oogonia. To produce 
oogonia after being transferred the fungus must draw upon its reserve 
materials and it might be thought that the dry weight of the mycelium 
would serve as a measure of the reserve materials available for the 
production of oogonia; but this was found not to be the case. 
