554 
ADRIAN J. PIETERS 
to solution 6. It is apparent that the fungus was not able to utilize 
sucrose in the presence of this strength of peptone while it made 
free use of maltose as shown by the record of number 6m which also 
contained o.i percent peptone but to which maltose had been added 
instead of sucrose. Numbers 8 and 9 contained the same amount 
of sucrose as 6 had and in addition 0.2 percent peptone, and 0.2 per- 
cent peptone and salts respectively, and on these mycelia were de- 
veloped the largest number of oogonia of any lot in the series. This 
large number of oogonia cannot be accounted for by the higher per- 
centage of peptone alone nor by the presence of salts alone, as then 
numbers 3 and ii should have given comparable results. It is evident 
that in numbers 8 and 9 the sucrose was used but the weight record 
indicates the use of only a small part of it. During the first seven 
days' growth the fungus was very well nourished as shown by the fact 
that the weights at the end of that time are among the highest. This 
rate of growth, however, was not maintained as is shown by the small 
increase in weight. The explanation is doubtless that in numbers 
8 and 9 part of the sucrose was changed to invert sugar owing either 
to too prolonged heating at high pressure while sterilizing, or to the 
presence of salts in the solution together with a high temperature. 
If this is true the fungus would find invert sugar present as soon as 
new growth began ; development would then be rapid in the next few 
days or as long as the invert sugar lasted. Upon the exhaustion of 
the invert sugar growth would slow down and the final weight would 
be less than that from solutions containing more available carbo- 
hydrates than sucrose. Further, if the fungus were removed before 
the invert sugar present was consumed it would be in the same physi- 
ological condition as it would have been if all the carbohydrate con- 
sisted of invert sugar. 
These theoretical considerations are supported by the facts of the 
experiment. After seven days numbers 8 and 9 had made as large a 
growth as any lot, but at the end of forty-eight days the total increase 
was 2.5 times the weight at the end of seven days, as compared with 
7-9 times the weight in the case of 8m and gm. Growth was at first 
rapid, then slowed down; the invert sugar was used up. That the 
mycelium at the end of seven days was in good condition is shown 
by the large number of oogonia produced. 
At the end of seven days and while the fungus in solutions 8 and 9 
was in the full enjoyment of an abundant supply of invert sugar the 
