296 Prof. P. F. Frankland. Influence of [Jan. 24, 



2nd Experiment (March llth, 1886). 



Air-plates CO 2 -plates 



(after 5 days). (after 8 days). 



Number of colonies from 1 c.c. f (a.) 15,515 (a 1 .) 0* 



f (a.) 15,1 

 I (6.) 18,! 



of the mixture I (6.) 18,950 (b 1 .) 



*0ri being transferred to a damp-chamber filled with air, there were 

 after three days 



(a') 1288 colonies. 

 (b') 1150 



In an atmosphere of carbonic anhydride B. pyocyaneus is thus not 

 only prevented from, multiplying, but the greater proportion of the 

 bacilli present are destroyed in the course of a few days. 



(&.) With Koch's Comma Spirilla (March llth, 1886), 



C0 2 -plates 

 Air-plates (after 8 days). 



Number of colonies from f (a.) 4183 (after 4 days) (a'.) 0* 

 1 c.c. of the mixture . . \ (b.) 4440 (after 5 days) (&'.) 



*These plates were then transferred to a damp-chamber filled with 

 air, and examined after three days, but no colonies were found. 



(c.) With Tinkler's Spirilla (March llth, 1886). 



Air-plates CO 2 -plates 



(after 4 days). (after 8 days). 



Number of colonies from 1 c.c. \ 10 mrr / (X ) 0* 



, . . / U,1U/ < , . N 



of the mixture J I (o .) 



*These plates" were then transferred to a damp-chamber filled with 

 air, and re-examined after three days, but no colonies were found. 



The deleterious effect of carbonic anhydride on the vitality of these 

 organisms is, therefore, far more intense in the case of the Koch and 

 Finkler spirilla than in that of the Bacillus pyocyaneus, for not only 

 can no colonies develop in the atmosphere of C0 2 , but the spirilla 

 are either destroyed or so weakened during eight days' exposure to 

 this gas that even on being transferred to an ordinary air-chamber no 

 colonies are developed. 



III. Experiments with Carbonic Oxide. 



This gas was prepared from potassium ferrocyanide and strong 

 sulphuric acid, and purified by passing it through a saturated solution 

 of caustic soda and then through a small tower tilled with slaked 

 lime, and finally through a plug of sterilised cotton-wool. 



The following experiments were made in the manner previously 

 described with the three micro-organisms mentioned : 



