RELATION BETWEEN VEGETATIVE VIGOR AND REPRODUCTION 557 
It will be noted that here sucrose has also had a marked effect, 
due doubtless, as before suggested, to the inversion of a part of the 
sucrose. In dextrose the growth was short and dense but did not 
fill the dish, while in maltose the growth was very dense and rapidly 
filled the dish with a mass of delicate hyphae. Possibly a lower 
concentration of maltose might have given better results. The growth 
in the haemoglobin-levulose solution was open but vigorous; oogonia 
appeared earlier than in the other dishes and the number formed was 
so much greater than the number produced by mycelium of the same 
origin in haemoglobin alone or in haemoglobin and dextrose that there 
can be no mistaking the conclusions that are indicated. The fact 
that these results confirm those secured when levulose was offered 
as a food during vegetative growth only make i; them especially 
significant. 
The results with S. ferax support the general conclusions arrived 
at in the experiments on A. racemosa. The weight of mycelium 
secured from any culture is no measure of the number of oogonia 
which that mycelium may be expected to produce when transferred 
to a suitable environment. There is however a minimum concentra- 
tion of food at and below which both the weight of the dry matter 
and the number of oogonia decrease. This minimum is about at 
O.I percent peptone for the production of both sporangia and oogonia. 
Levulose is especially valuable as a food for the formation of 
oogonia; dextrose is not used as freely and sucrose not at all unless 
previously inverted by other agencies, while maltose is readily used. 
Experiments with S, monoica 
S. monoica was used because it normally has an antheridium on 
each oogonium and oogonia are freely produced, even under some- 
what adverse conditions. This species is closely related to 5. ferax, 
and experiments with it might be expected to confirm the conclusions 
drawn from the results of previous experiments. It was also thought 
that some light might be thrown upon the kind of food that is best 
for the production of antheridia. Cultures were made in flasks 
containing 200 cc. of liquid in the same manner as for S. ferax series 
III; after growing five days these cultures were transferred to 0.05 
percent haemoglobin. 
Table XV gives the complete record for this set. 
