. Chemical embryology. Embryology. 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 , 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 Energet
. Chemical embryology. Embryology. 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 , 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 178 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. Investigator Organism (%) Stephenson & Whetham Timothy Grass Bacillus 27-0 Becking & Parks Nitrobacter 7-9 ,, Mtrosomonas 5-9 ,, B. niethanicus 15-1 Ruhland B. pycnoticus 20-5 Waksman & Starkey Thiobacillus thiooxidans 6-2 Beijerinck Thiobacillus denitrificans 8-7 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
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Keywords: ., bookcentury1900, bookpublishernewyorkthem, booksubjectembryology
