ENERGY TRANSFORMATION 



417 



the particular culture. The mycelium from this culture gave on combustion 

 3.55 Cal. = U'. The ratio of the energy stored in the mycelium to the metabo- 

 lizable energy U is thus found to be 3.55 -5- 5.95 = 59.6 per cent, or very near 

 the above figure, calculated from other data. 



When fully developed mycelium is placed in Czapek's solution, it 

 does not grow further but forms C0 2 ; this permits the calculation of a 

 minimum value for maintenance energy. The consumption of glucose 

 by Asp. niger is at any instant the sum of two terms: (1) a term pro- 

 portional to the rate of growth, which represents the amount of 

 glucose which should disappear to form the substance of the mycelium 



TABLE 28 

 Relation of metabolic products of fungi to one another and to sugar consumed 



(pentoses) 



Days of incubation 



_ _ . weight of CO2 



Respiration coefficient or — — . . . 



weight of dry fungus 



_ . _ . weight of sugar consumed 



Economic coefficient or 



weight of dry fungus 



. . . , carbon of C0 2 X 100 



Respiration equivalent or . . . 



carbon of sugar 



_,, M . . . carbon of fungus X 100 



Plastic equivalent or .... 



carbon of sugar 



Asp. niger 



1.5 



3.5 



41 



47 



28 



2.5 



2.4 



55 



36 



Pen. glaucum 



2.5 



3.2 



54 



39 



28 



4.5 



4.4 



70 



28 



and (2) a term proportional to the weight of mycelium already formed 

 at that instant, which represents the consumption of sugar for 

 maintenance. 66 



There is a definite relation between utilization of sugar, growth of 

 fungi and evolution of C0 2 , as shown in table 28. 67 The "economic 



60 Further information on energy utilization by fungi and yeasts, in the absence 

 of an excess of oxygen, is given by Kostytschew, S., and Afanasjeva, M. Die 

 Verarbeitung verschiedener organischer Verbindungen durch Schimmelpilze 

 bei Sauerstoffmangel. Jahrb. wiss. Bot., 60: 628-650. 1921; Rona, P., and 

 Grassheim, K. Studien zur Zellatmung. I. Beitriige zur Atmung der Hefezel- 

 len. Biochem. Ztschr., 134: 146-162. 1922; Meyerhof, 1925 (p. 413). 



67 Peterson, Fred and Schmidt, 1922 (p. 242). 



