294 Prof. P. F. Franklancl. Influence of [Jan. 24, 



(a.) With B. pyocyaneus (Green Pus). 

 1st Experiment (March 4th, 1886). 



Air-plates H-plates 



(after 2 days) . (after 4 days) . 



Number of colonies from f (a.) 22,412 1 00 K Ark , 



T , , . , } ST. \ etc* /?tfi f ^^jOUU 



1 c.c. of the mixture. . I (&.) 22,651 J 



The appearance presented by the plates developed in the hydrogen- 

 chamber and those developed in air was very different. On the 

 former the colonies were decidedly larger, less sharply defined, fainter 

 in colour, and of more radiated structure than those on the air- 

 plates. 



2nd Experiment (March llth, 1886). 



Air-plates H-plates 



(after 5 days). (after 7 days). 



Number of colonies from f (a.) 15,515 ] , - 200 (a'.) 12,365 1 -, 9 OAA 



1 c.c. of the mixture . . { (6.) 18,950 / (6'.) 12,262 j 



The hydrogen-plates again showed the characteristic appearances 

 mentioned above, many of the surface colonies having reached a 

 diameter of 1 cm. 



3rd Experiment (March 29th, 1886). 



Air-plates H-plates 



(after 4 days) . (after 7 days). 

 Number of colonies from 1 c.c. 



of the mixture 6124 5600 



In this case again the hydrogen-plates had the same characteristic 

 appearance, the colonies on the surface being surrounded by a com- 

 plete circular zone which exceeded by many diameters the original 

 size of the colony. 



From these experiments it is seen that the development of the 

 Bacillus pyocyaneus is only slightly affected in an atmosphere of 

 hydrogen; the colonies, however, grow more slowly and present a 

 distinctly different appearance. 



(6.) With Koch's Comma Spirillum. 

 1st Experiment (March 15th, 1886). 



H-plates 

 Air-plates. (after 7 days) . 



Number of colonies from f (a.) 4183 (after 4 days) (a'.) 6767 

 1 c.c. of the mixture . . \ (6.) 4440 (after 5 days) (&'.) 8260 ' 



The colonies on the hydrogen-plates were smaller than those on the 



