zi8 



THE QUARTERLY REVIEW OF BIOLOGY 



Bacf. coli gave an increased count under 

 45 and 70 pounds extra CO a pressure up to 

 ten days. Bact. typhosum increased in 

 numbers under low (45 pounds) pressure. 

 Complete sterility was evidently not 

 reached within 30 days, when zo organ- 

 isms per cc. were inoculated into ginger 

 ale. 



Hunziker (19x4) reported his experi- 

 ments concerning the effect of carbon 

 dioxide on butter. Two lots of butter 

 were churned experimentally on a com- 

 mercial scale. One-half of the cream 

 was given carbon dioxide treatment. No 

 bacterial counts are given, but the 

 examination showed that the carbonated 

 butter had turned rancid, and the score 

 dropped from 89 points (fresh butter) to 

 83 points at the end of iz weeks. This 

 would indicate that carbonation cannot 

 be relied upon to prevent bacterial 

 deterioration of butter. 



Prucha, Brannon and Ruehe (1915) 

 concluded that if any appreciable benefit 

 is to be expected from the carbonation of 

 butter, it is necessary to store the butter 

 in an atmosphere of C0 2 in an air tight 

 container. 



EFFECT ON BACTERIUM ABORTUS 



Theobald Smith (192.4) reported studies 

 with Bact. abortus, which had extended 

 over a period of two years. It is note- 

 worthy to observe that freshly isolated 

 strains yielded better growth under C0 2 

 than under ordinary atmosphere. Accord- 

 ing to him, certain strains may not develop 

 at all in the open culture tube. It was 

 found, further, that by removing the 

 C0 2 with sodium hydrate, growth is 

 inhibited completely in freshly isolated 

 strains, and materially retarded in old 

 strains. It developed further that as 

 high as 100 per cent carbon dioxide could 

 be tolerated by the organism. There was, 

 however, some retardation of growth. 



Growth of certain strains appeared in 

 eleven day old tubes, under carbon dioxide, 

 which had shown no indications of 

 development under ordinary atmospheric 

 conditions. The author suggests that 

 further studies may show that Bact. 

 abortus (Bang) is the only pathogenic 

 organism which possesses such a C0 2 

 relationship. It is further pointed out 

 that the different strains of Bact. abortus 

 fall into two groups, parasitic and sap- 

 rophytic. In a later work (19Z6) the 

 same writer stated that this relationship 

 to C0 2 may serve a useful purpose in 

 differentiating Bact. abortus strains into 

 the bovine type on the one hand, and the 

 so-called vaccinal or persistent udder 

 strains on the other. 



Rockwell (19Z4) advocated the use of ! 

 carbon dioxide in anaerobic cultures, and I 

 presented experimental evidence of suc- 

 cessful cultural work by this method, with 1 

 CI. welchii, CI. tetani, an organism from I 

 chronic bronchitis, and with CI. botulinum. . 



Sierakowski and Zajdel (19Z4), discuss- • 

 ing the role of carbon dioxide in hermet- 

 ically sealed bacterial cultures, observed ! 

 that this gas adjusts the final H-ion con- ^ 

 centration to pH 6.8. This they claimed 

 to be true in all bacterial cultures. Evi- 

 dence to this effect was offered for B. , 

 dysenteriae (Flexner), Bact. typhosum, Bact. 

 paratyphosum A, B, and C, Bact. coli, . 

 V. cholerae, C. diphtheriae, Prot. vulgaris 

 and Staphylococcus. Five day old cultures, 

 when stoppered, do not acidify, that is 

 reach a pH of 6.8, since these are : 

 evidently dying off and do not produce 

 C0 2 . According to them, production of 

 C0 2 may be taken as an indication of 

 viability in a culture. 



Novy and Soule (19Z5) arrived at the 

 conclusion that M. tuberculosis does not 

 require C0 2 for its development, and that 

 it is not inhibited, therefore, by the 

 removal of carbon dioxide from the cul- 



