ENERGY TRANSFORMATION 391 



atmosphere. These results allow the calculation of the amount of 

 energy actually utilized by the organism for synthetic purposes. As 

 pointed out above, 18.8 Cal. are formed in the oxidation of 1 mol (14 

 grams) of nitrogen in the nitrite form. The heat of combustion of 

 1 mol (12 grams) of pure carbon to carbon dioxide in solution is 103 

 Cal. If the calculation is based on the formation of a carbohydrate, 

 the energy required is even larger (113 Cal.) because of the addition 

 of water. To gain this number of calories, 135 times as much nitrate 

 nitrogen is formed as there is carbon assimilated and changed into an 

 organic form, or 



Milligrams of nitrogen oxidized (NOl) ..„_ 

 Milligrams of carbon assimilated (C0 2 ) 



One can thus calculate that for 12 grams of carbon (mol of C0 2 ), 1620 

 grams of nitrogen (135 by 12 grams) are transformed. This corre- 

 sponds to 115.7 mols of N0 2 (1620: 14) L Since 18.8 Cal. of heat are 

 liberated per mol of N0 2 oxidized to N0 3 , the total will be equivalent 

 to 2175 Cal. (115.7 by 18.8). Out of this number of calories liberated, 

 only 113 Cal. are gained in the synthetic process (assimilation of one 

 mol of carbon as C0 2 ); this means that only about 5.2 per cent of the 

 energy liberated in the oxidation process is utilized for doing work, in 

 the synthesis of protoplasm out of C0 2 and inorganic nitrogen and 

 minerals. 



The observations of Coleman 15 that the nitrate bacteria require 

 carbon dioxide only at the start of the growth period but do not require 

 it for further development, as well as the remarks of Beijerinck 16 that 

 nitrate forming bacteria do not show any definite proof for chemo- 

 synthesis of carbon dioxide, were based on inaccuracies in the deter- 

 minations. The earlier observation of Winogradsky that the nitrate 

 bacteria can build up their body substance without the aid of foreign 

 organic matter has been confirmed. 



In carrying out these experiments, Meyerhof used 50-cc. portions of 

 nutrient solution consisting of chemically pure salts in water distilled 

 over sulfuric acid. The solution was placed in clean flasks, and inocu- 

 lated with a fresh culture of the organism. The air passing through the 

 cultures was first passed through four per cent KMn0 4 solution, pure 

 concentrated H2SO4 and TV NaHC0 3 . The growth of the culture was 



15 Coleman, L. C. Untersuchungen iiber Nitrifikation. Centrbl. Bakt. II, 

 20: 401-420, 4S4-514. 1908. 

 18 Beijerinck, 1914 (p. 76). 



