192 
Journal of Agricultural Research 
Vol. XXI, No. 4 
METHOD OF TAKING RESULTS 
At the end of two weeks the flasks with their contents were weighed 
again, and the mycelium was filtered out with the aid of suction into 
previously burned and tared alundum crucibles. The fungous felts 
were washed by pouring through the crucibles a quantity of distilled 
water and were then dried to constant weight in a vacuum oven at 6o° C. 
The glucose content of all the solutions was determined by means of 
the Fric saccharimeter. 
In determining the sugar content of the 10 and 20 per cent solutions, 
three and two times the normal weight of the solutions, respectively, 
were used, while the normal weight was taken in all the higher concen¬ 
trations. The solutions were then made up to 100 cc. with distilled 
water and polarized through a 200-mm. tube. 
The control solution produced no visible polarization. 
The osmotic pressure and saccharimeter readings were made with 
freshly filtered solutions on the day the experiment was terminated. 
The depression of the freezing point was determined with a Beckman 
thermometer in an ordinary DeWar flask, the solution being cooled by 
the evaporation of ether. The osmotic pressure values were calculated 
from the freezing points obtained by one of the two formulas given by 
Harris and Gortner ( 14 ). When these were sufficiently low, as in series 
I, II, III, and IV, the first formula was used and the osmotic pressure 
was taken from their table, or from that given by Harris ( 13 ). This 
takes into consideration the error due to undercooling, whereas the 
second formula does not. 
The changes in acidity of the solutions were determined by the use of a 
potentiometer, with the arrangement of Michaelis {23). The measure¬ 
ments were made in a closed vessel provided with a dip hydrogen elec¬ 
trode similar to that of Bovie (j), except that an exit tube was provided 
for the hydrogen. In most cases a day or two intervened before the po¬ 
tentiometer readings were made. In such cases the solutions were ster¬ 
ilized by steaming for 20 minutes and were then kept at a temperature of 
about 9 0 C. until used. A number of preliminary tests with these and 
other solutions showed that the hydrogen-ion concentration was not 
appreciably altered by steaming. 
EXPERIMENTAL BATA 
PERCENTAGE OF GLUCOSE REMAINING AT THE END OF THE EXPERIMENT 
As already pointed out, the culture solutions were prepared to contain 
glucose in concentrations from o to 60 per cent. In the tables which 
follow, the controls are the flasks of the different series which were not 
inoculated. 
An inspection of the control columns in Table I shows how nearly the 
solutions made roughly to contain the same percentages of sugar agree 
