976 



ENERGETICS AND ENERGY-SOURCES [pt. m 



Efficiency 

 (Rendement Energet 



Tangl found. Since the basal metabolism is included in this estimate, 

 and since that might naturally be expected to be high in the early 

 stages when the embryo is very minute, and has a large surface in 

 proportion to its size, one can understand that the efficiency, the 

 A.E.E., would then be very low. 



Another way of interpreting ^ig. 260 would be by the recapitula- 

 tion theory. Perhaps the most striking chemical attribute of the bacteria 



and yeasts is their high energy ^^^ Apparent Energetic 



turnover : Horace Brown, for ex- 

 ample, showed that a yeast cell 65|- 

 would ferment its own weight of 

 maltose at 30° C. in 2-2 hours, 

 and at 40° C. in 1-3 hours. This 55 

 metabolic level would be about 

 100 times as high as that of an 

 adult man. And Haacke has cal- 45 

 culated that certain lactose fer- _ 



40 



menting bacilli destroy from 1 78 



to 14,980 times their own weight ^^s- 2^°- 



of lactose per hour. Parallel with this furious onslaught on the 



nutrient material of their environment goes a very low efficiency^, 



figures for which are available in a number of papers : 



Efficiency 



In discussing these facts Stephenson suggests that the breakdown 

 of a substance such as sugar by the yeast-cell or a bacillus is con- 

 ditioned mainly by the concentrations of cells (enzymes) and substrate, 

 irrespective of whether the cells can benefit by the energy liberated. 

 Thus the energy liberated by micro-organisms would be no measure 

 of their metabolic needs but simply the result of unprotected enzymes 

 acting upon the appropriate pabulum. "If such a view be correct" 



^ But it must be understood that micro-organisms have really no definite efficiency; 

 it varies according to their environment, and they have no means of adjusting it. 

 Bacteria "killed" by ultra-violet light continue to oxidise at almost the normal rate, 

 though incapable of growing, and in yeast cultures fermentation and growth are quite 

 dissociable. When growth ceases the efficiency is nil, but in certain conditions it may 

 be as high as 59 % (Terroine & Wurmser on moulds) . 



