572 
ADRIAN J. PIETERS 
The Value of Sucrose 
The records of the tests with solutions containing sucrose have 
been difficult of interpretation throughout the work. Under the 
discussion of Table X it was pointed out that the close agreement in 
the weight between the mycelium out of o.i percent peptone and 
that out of peptone and sucrose, as compared with the results when 
maltose was used, showed that little if any sucrose was utilized by 
the plant. The mycelium out of solution 8, however, showed not 
only a considerable increase in weight, but also in the number of 
oogonia formed over that out of No. ii, the difference between the 
two solutions being the addition of sucrose in num^ber 8. 
The results recorded in Table XIII are similar, the fungus growing 
in a solution containing sucrose having made little more weight than 
that grown in peptone alone, and the number of oogonia formed on 
the mycelium out of sucrose and peptone is nearly the same as that 
from the mycelium out of peptone alone. At the time the experiments 
were carried on the writer was not aware of the work of Noel Deerr 
('lo) on the effect of high temperatures on the inversion of sucrose. 
Deerr found that when sugar solutions in pure water were heated in 
an autoclave to a temperature of iio° no invert sugar was formed 
but that above that temperature a rapid increase in inversion with 
equal increments of temperature took place. Salts, as the nitrates of 
potassium, sodium and others, and the sulphates, as that of mag- 
nesium, increased the amount of inversion. The above facts offer 
an explanation of the results obtained with sucrose. The solutions 
used were always sterilized in an autoclave at a temperature of about 
Ii2°-i20° C, but occasionally the temperature rose to 125° C. Ac- 
cording to Deerr's results a small amount of invert sugar should have 
been made in practically every solution in which sucrose was used 
and it will be noted that the weights secured from mycelia out of 
peptone and sucrose are consistently a trifle greater than those from 
mycelia out of peptone alone. When salts were added, and occasion- 
ally when peptone and sucrose alone were present, a more marked 
increase in weight resulted. 
In order to determine whether invert sugar was formed under the 
conditions prevailing in the above described experiments a series of 
solutions was made up containing in each case o.i percent peptone 
and 1/50 molecular sucrose. One set was sterilized at 110° C, one 
at 115° C. and the other at 125° C. Another series was also prepared 
