STUDY OF THE IMMUNITY AGAINST BACILLUS PYOCYANEUS 7 



the general colour of the medium was a yellowish-brown. On shaking 

 violently, this was instantly converted into a bright grass green colour 

 from the action of the oxygen of the air, and the formation of pyocyanin 

 and fluorescent green. In the course of time the consistence of the 

 medium alters, so that, instead of the limpid clear broth, a thick stringy 

 mucinous-like material occupies the whole flask. 



Filtration Experiments. 



Cultures of the bacillus in broth were taken at various times and 

 passed through the Berkefeld filter. With young cultures up to 7 days 

 this was easy, but when the mucinous cultures had to be dealt with, 

 filtration was found to be extremely difficult, even the most open-pored 

 Berkefeld filters becoming rapidly clogged up. 



Filtrate from 2 day old broth culture. 



Filtrate from 7 day old culture. 



('63) 



M I 



