96 AERATION AND AIR-CONTENT. 



When the sugar is mannite this transformation is accompanied by 

 the evolution of hydrogen, and this is notably the case whenever 

 bacterial decomposition sets in. 



Sadebeck (1881) observed that the spores of Ascomyces tosquinetii, 

 when placed in a sugar solution in the complete absence of oxygen, 

 exhibited an extraordinarily energetic germination, even better and 

 more rapid than in the air. 



Foth (1889 : 279) observed that carbonic acid, like other acids, 

 exerted a strong limiting action on the budding of yeast, and that its 

 fermentative activity was influenced by even small amounts, while 

 different races of yeast were resistant to C0 2 in varying degrees. 



Frankel (1889 : 332) found carbon dioxid to limit the growth but 

 not to kill rose yeast and black yeast, while the true yeasts thrived 

 in it. He divided the bacteria into several classes, namely, those 

 which grow as well in C0 2 as in air, those which can develop in C0 2 

 but whose growth is greatly reduced by it, and those which can not 

 develop at ordinary temperatures in pure CO 2 , but can in incubation 

 temperatures. The remaining bacteria, which are in general sa- 

 prophytes, do not develop in CO 2 , but are not killed by it, and they 

 grow again when placed in air. Finally, there are bacteria which 

 are killed in C0 2 , among which are the most important pathogenic 

 forms. 



Frankland (1889 : 13) found the widest range of response to un- 

 favorable conditions among one-celled organisms, the majority of 

 individuals dying quickly, while a few remained unharmed. 



D' Arson val (1891 : 667) showed that carbon dioxid under a pres- 

 sure of 45 atmospheres was a sterilizing agent of great significance, 

 replacing the autoclave. While the resistance of the bacteria was 

 very variable, all were killed after long treatment at a temperature 

 of 40 C. 



Freudenreich (1892 : 7) found that the anthrax bacillus and one 

 other found in milk were resistant to a C0 2 -pressure of 80 to 90 

 atmospheres and an oxygen-pressure of 60 atmospheres, combined 

 with a rise of temperature to about 65 C. 



Van Slyke and Bos worth (1908) have found that carbon dioxid 

 under pressure exerts a marked retarding action upon the develop- 

 ment of lactic-acid bacteria, to the extent that fresh milk so treated 

 exhibits practically no increase in acidity after 9 months at 40 to 

 60 F. 



Bosio (1893 : 61) stated that carbon dioxid under pressure sup- 

 pressed the development of Mycoderma aceti and M. vini in beer. 



Lopriore (1895 : 621) observed that spores of Mucor mucedo could 

 not germinate in pure CO 2 when they remained in the gas 3 months, 

 but that they would germinate and grow normally when again 

 brought into air. He found, moreover, that spores germinated at 

 90 per cent CO 2 and that the number of germinated spores increased 



