ON THE Economic Coefficient of Sugar 467 



standard sugar solution eacli time. The factor (Allen's Industrial 

 Chemistry, vol. I., p. 226) of 10 cc. Fehling solution =0.0475 

 cane sugar after inversion was used as the basis of all calculations. 



The dry weight of fungus was determined in the usual way, 

 the crop having been collected on a weighed filter was dried in an 

 oven at the temperature of about yo^ C. to constant weight. 



In the absence of thermostat the cultures were grown at the 

 ordinary room temperature in the laboratory or at a somewhat 

 higher temperature in a room which served also as a conservatory. 

 The cultures were consequently subjected to some fluctuation of 



I 



temperature, possibly somewhat to the disadvantage of the results 

 obtained. It would, undoubtedly, have been preferable to have 

 grown the Stcrigniatocystis cultures at a point nearer the optimum 



I 



for that fungus between 30° and 34^ C. In the case of the Pcni- 

 dlliuni the room temperature approximated more nearly the lower 

 optimum of that fungus. In spite of the variations, however, the 

 results for both correspond satisfactorily, the Stcrigniatocystis cul- 

 tures being allowed to grow for a somewhat longer period than 

 would otherwise have been necessary. 



It would', indeed, have been well to have determined the res- 

 piration quotient in relation both to the increased growth and the 

 economic coefficient but the writer was unable at the time to do 

 so, although, it is his intention to experiment in this line in the 

 future. The facts demonstrated, however, show much as to the 

 economic coefficient of the sugar in relation to the abnormal 

 growth caused by chemical irritation despite the fact that at pres- 

 ent they cannot be compared with the CO^ coefficient. 



It will be seen by comparison with the results of Kunstmann* 



■ 



that the averages of the economic coefficient obtained from the 



] 



control cultures is correct. This average approximates 2.00 for 

 the ratio between the amount of sugar used for the dry weight of 

 fungus produced or, as may better be expressed, 0.50 grm. of dry 

 substance for each gram of sugar consumed. In table I. of Kunst- 

 mann's paper the average coefficient for those cultures grown be- 

 tween the temperatures of 17° and 25°C. is 2.05 = 0.49. This 

 serves as a check for the results recorded herein. 



■'^ Ueber das Verhallniss zvvischen Pilzernte u. verbrauchter Nilhrung. Inaug. Dis- 

 sert., Leipzig, 1895. 



