214 
Journal of Agricultural Research 
Vol. XXI, No 4 
addition of brom phenol blue the solution changes to a deep blue color 
and when slightly acid to a lemon-yellow. 
EXPERIMENTAL DATA 
RATE OF RESPIRATION 
The rate of respiration of the different fungi expressed in C 0 2 produc¬ 
tion is shown by the curves in figure i, where the abscissae represent 
days and the ordinates the amount of C 0 2 produced daily in grams. 
Pays 
Fio. i.—Rate of respiration of various fungi: i, Rhizopus tritici; a, Diplodta tubericola; 3, Mucor racemosus; 
4, Penicillium sp.; 5, Sclerotiuvi bataticola; 6, Fusarium acuminatum; 7, Botrytis cinerea. 
The figures used in plotting these curves are in most cases the averages 
of two parallel tests. One familiar with the physiology and growth of 
fungi is aware that the same nutrient medium, the same temperature, 
and other environmental factors do not meet the requirements of all 
fungi equally well. In order to make the results comparable, a uniform 
standard of conditions for all the organisms was established as nearly as 
possible. They were all grown in an incubator maintained at a constant 
temperature of 29 0 C. in the dark. 
An inspection of the curves shows that three organisms—namely 
Penicillium sp., Botrytis cinerea , and Sclerotium bataticola produced a 
quantity of C 0 2 in excess of 2 gm. in a single day, while the four remain¬ 
ing organisms produce a relatively small amount. The data show also 
that those organisms which grew rapidly produced a comparatively small 
amount of C 0 2 , reaching their maximum in a short time after the culture 
flasks were inoculated and declining steadily thereafter. Rhizopus 
