140 Messrs. E. C. Grey and E. G. Young. 



by B. colt previously grown anaerobically ; the one is the absence of lactic 

 acid and the other the absence of succinic acid from the products of decom- 

 position. In place of them acetic acid appears. 



In order to make clearer the effect which aerobic and anaerobic growth 

 has upon the subsequent fermenting power of the bacteria, Table IV is 

 included wherein the anaerobic fermentations described in this communication 

 are compared with typical anaerobic fermentations which have been carried 

 out with bacteria grown aerobically as described in Parts II, III and IV of 

 this series. 



Table IV. — A Comparison of the Products of the Anaerobic Fermentation 

 of Grlucose by B. coli, grown previously Anaerobically and Aerobically. 



Products. 



Products as percentages of the glucose consumed.* 



Bacteria grown aerobically. 



Bacteria groim anaerobically. 



Hydrogen 



Carbon dioxide 

 Formic acid ... 

 Acetic acid ... 

 Lactic acid ... 

 Succinic acid 

 Alcohol 



Total 



0-33 

 16 -37 



2-76 

 19-34 

 28 -47 

 20 -32 

 11 -04 



98 -63 



•21 

 •24 

 •29 

 ■02 

 ■46 

 •23 

 •36 



99 •SI 



■35 

 ■38 

 ■22 

 •56 

 •93 

 •36 

 •06 



0^61 

 27 ^33 



16 •es 



8 ^67 

 Nil 

 9^83 

 7-33 



97 ■Se 70 •45 99 •OO 



27 •SO 

 12 ^64 

 34 •SS 

 8^44 

 0^58 

 15 -66 



0^36 

 37 •32 



8 '75 

 41 -07 



1 -25 



Nil 

 10 -00 



0^18 

 23 -03 



5 ■IS 

 57 •68 



2^68 



NU 



5^00 



98 -75 93 ^75 



Fermentations all anaerobic. 



Note on the Relation of Oxygen to the Growth of B. coli communis. 



The organism we have been using has frequently been described as a 

 facultative anaerobe. It is easy to see that tbe growth is much more 

 extensive on agar in air than in hydrogen. Under comparable conditions we 

 obtained 70 mgrm. of B. coli (dry weight) after anaerobic growth on agar, and 

 280 mgrm. after aerobic growth. In the absence of oxygen, B. coli grows 

 better in a fluid nitrogenous medium than on an agar surface. It has already 

 been shown (Part III) that when an emulsion of bacteria is mixed with 

 glucose solution the bacteria while carrying out a rapid fermentation of the 

 glucose (1 grm. per hour per gramme of bacillus) are rapidly dying, and in 

 this death process no lactic acid is formed. Subsequently a new generation of 

 bacteria replaces the old and these give rise to lactic acid. B. coli would thus 

 appear to have two distinct forms of metabolism. "When the organisms have 

 had an immediate past history of life in air they require oxygen for their 

 continued existence in this form ; if they must ferment anaerobically they die 



