180 



PHYSIOLOGY OF BACTERIA 



There is a nitrogen gain of 1.33 kg., doubtless due to the 

 great probable error in analysis. 



Of the total nitrogen offered, 59.03 kg., the new 

 growth of the yeast contained 36.56 — 7.85 = 28.71 kg. 

 or 48.6%. 



II. RELATIONS BETWEEN GROWTH AND 

 FERMENTATION 



(a) EFFICIENCY OF UTILIZATION OF ENERGY 



Most bacteriologists hold the viewpoint that fer- 

 mentation (as defined by Hugo Fischer, see page 24) 

 is the source of energy which is needed by the cell for 

 repair and for new construction, i.e., growth. The 

 amounts of energy necessary for growth will vary con- 

 siderably with conditions. It might seem that bacteria 

 growing in a peptone solution would need no energy at 

 all, because the combustion heat of the food is as high as 

 that of the bacteria (see Table 42 from Rubner, 1904a) ; 

 and bacteria growing on fat would even have a surplus 

 by just converting every bit of the fat into carbohydrate 

 and protein. 



Table 42. — Combustion Heats of 1 Gm. of Solids 



Calories 



Calories 



Peptone 



Gelatine 



Meat extract 



Dextrose 



Sucrose 



Fat, about 



Penicillium glaucum . . 



5,492 

 4,992 

 3,514 

 3,740 

 3,950 

 9,200 

 4,753 



Penicillium glaucum with 

 spores 



Top yeast 



Bottom yeast 



Proteus vulgare 



Bad. prodigiosum 



Bad. prodigiosum, old cul- 

 ture 



5,359 

 4,475 

 4,554 

 4,643 

 4,764 



4,442 



This assumption has two errors. It does not take 

 into consideration that the architecture of the bacterial 



