RELATION BETWEEN VEGETATIVE VIGOR AND REPRODUCTION 565 
sucrose solution and in some the formation of oogonia and oospores 
was all that could be desired. The results, as a whole, however, are 
not regular enough to warrant the statement that the failure of some 
mycelia to produce oogonia was due to the preceding conditions of 
growth. This however does not affect the general value of the 
results as pointing to the conclusions previously reached. It is true 
that the mycelia with the largest number of oogonia and oospores 
are also among those having the greatest weight, but not all of the 
latter class have developed large numbers of oogonia (see numbers 
12, 15, 17), while the records of several numbers show a good develop- 
ment of oogonia together with weights one half to one third as great 
as those from other lots. When the solutions containing sucrose are 
not overheated there is clearly little invert sugar; the fungus makes 
practically no more growth in such solutions than in peptone alone 
and the number of oogonia is about the same on mycelia from all 
these solutions; compare the record of numbers 2 and 6, 3 and 10. 
The weight of mycelium out of levulose-peptone solution was nearly 
the same as that out of peptone alone and the mycelium out of the 
former solution responded to the peptone-sucrose environment by an 
unusually vigorous growth of delicate hyphae which soon filled the 
dish. This phenomenon was observed in two out of three series of 
experiments while in a third oogonia were formed on mycelium out of 
levulose-peptone but these were not nearly so numerous as on other 
mycelia. The influence of levulose when used as a culture medium 
for Achlya prolifera was certainly against the formation of oogonia. 
The addition of salts produced a marked increase in growth with all 
the sugars, but most with the sucrose, doubtless because of the ex- 
tensive inversion of the sucrose under the action of the high tempera- 
ture and salts. 
Two other series of experiments were made with A. prolifera, and 
in both the results were similar .to those recorded for series V. In 
one series a transfer solution weaker in peptone (0.0 1 percent) and 
stronger in sucrose (1/200 molecular) was used in the hope that this 
would lead to a better development of the oospores. The results 
were, however, no more uniform than before as only a small pro- 
portion of oogonia in any lot contained oospores. In another series 
various salts were added to the peptone-sugar solutions and to the 
peptone alone. The salts used were various phosphates, nitrates and 
sulphates, the same as were used in the experiments with S. monoica, 
