RELATION BETWEEN VEGETATIVE VIGOR AND REPRODUCTION 53 1 
studied the effect of various foods consumed by the myceHum before 
transfer. 
The Problem 
The question was raised therefore, "What is a 'well nourished' 
mycelium?" and naturally the question of what constitutes a good 
nutritive solution followed. This work was commenced at Heidel- 
berg, under the direction of Prof. Dr. Georg Klebs, who agreed with 
the writer that a culture medium, in which the fungus can attain the 
greatest dry weight in a given time under favorable conditions, is 
generally to be considered the best nutritive medium. The question 
which the writer set himself to answer therefore, is the following: 
Will a nutritive medium in which a species of water mold produces the 
greatest amount of dry matter in a given time also give to that myce- 
lium when transferred to a suitable medium, the power to form more 
reproductive organs, than are produced by a mycelium grown in 
a poorer medium, measured by dry weight of mycelium produced? 
Or, in other words, is there a direct and necessary relation between 
vegetative growth and reproductive capacity? 
Generally in cultures of other fungi the reproductive bodies, when 
formed under these conditions, are produced while the mycelium 
remains in or on the culture medium in which its vegetative growth 
has taken place; not so with the Saprolegnias. If satisfactory results 
in the production of sporangia or of oogonia are to be obtained, these 
plants must be transferred from the solution in which they have been 
grown, to another and weaker solution. When the plant is trans- 
ferred to the second solution, it finds itself in a new environment. 
This may differ from the old merely in concentration and in the 
absence of the poisonous products of metabolism, which have accumu- 
lated in the old solution, or it may differ from the latter in chemical 
composition. As Klebs has pointed out ('99), whatever the chemical 
nature of the second solution may be, it must, if oogonia are to be 
formed, be of such character and concentration, that a slight growth 
can take place. If the solution is too poor in food, sporangia will 
appear and perhaps exhaust the mycelium, while if the food is too 
good vegetative growth will prevent reproduction. 
If the protoplasm produced by the consumption of all kinds of 
foods is alike we may expect that the nature of the changes observed 
after transfer will depend wholly on the new environment; but if the 
food used during vegetative growth can affect the character of the 
