EXPERIMENT STATION BULLETINS. 



289 



XVIII. ACTION OF CARBON DIOXIDE UPON BACTERIA WHEN CULTIVATED IN 



BOUILLON. 



The results given in the following table were obtained by taking bouillon tubes and 

 inoculating two sets; one set was placed in the air as check and the other was placed in 

 S8.5 per cent carbon dioxide. The methods of measurement employed were identical 

 with those in the previous milk culture experiment. 



TABLE XVI. 

 ACTION OF CARBON DIOXIDE UPON BACTERIA WHEN GROWN IN BOUILLON. 



No. of micro-organism. 



119. 

 120. 

 121. 

 122. 

 123. 

 124. 

 125. 

 126, 

 127, 

 128. 

 129 

 130 

 131 

 132 

 133 

 134 



Tubes grown in 88.5% CO.-. 



No growth 



♦Retarded development.. 



No growth 



Retarded development. . . 



No growth 



Retarded development. . . 



No growth 



No growth 



No growth 



Retarded development . . 



No growth 



tSlight development 



Retarded development. . . 



Slight development 



No growth 



Slight development 



Tubes in air as check. 



Dense growth. 

 Dense growth. 

 Slight development. 

 Dense growth. 

 Dense growth. 

 Dense growth. 

 Dense growth. 

 Dense growth. 

 Dense growth. 

 Dense growth. 

 Dense growth . 

 Dense growth. 

 Dense growth. 

 Dense growth. 

 Dense growth. 

 Dense growth. 



* Retarded development. Slightly less cloudy than air tubes, 

 t Slight development. Growth only perceptible. 



Table XVI clearly demonstrates also that the density of development of the two 

 sets of bouillon tubes varies, and that in some cases there is no development so far as 

 cloudiness is any indication, while in other cases there has only been a retarding action. 

 The results in this table agree with those obtained in plate and milk cultures. (Tables 

 X, XII, XIII, XIV, XV.) 



XIX. HOW AN ATMOSPHERE OF CARBON DIOXIDE INFLUENCES THE CHARACTER 



OF THE FERMENTATION OF MILK. 



To pursue a study of this subject we have felt it necessary to use the so called Hesse 

 flasks. These flasks were filled with milk which after sterilizing were inoculated. The 

 air in the flasks above the milk was expelled by passing carbon dioxide until complete 

 substitution had been made. Since as shown in the previous tables the action of 

 carbon dioxide is marked by its retarding or inhibiting the growth of bacteria it is 

 not necessary to consider it further but rather to study the peculiar influence which 

 the gas exerts upon the character of the fermentation of milk caused by specific 

 bacteria. 



37 



