342 APPLIED BACTERIOLOGY 



described by Dr. A. C. Houlston (Local Government Board 

 Eeport, Supplement containing medical officer's report, 

 1893-4), who obtained them from peat. These two bacteria 

 give rise to acidity when grown in peat-infusion, which 

 has a great solvent action upon lead. It is to these 

 organisms that is attributed the cause of the lead- solvent 

 power in waters from peaty districts. 



Photo-Bacillus Baltieum — Photo-Bacillus Fischeri — Photo- 

 Bacillus Fluggeri. — These three phosphorescent bacteria 

 give rise to the phosphorescent appearance seen in the 

 sea in various places, on fish, decaying wood, etc. The 

 are short rods, which frequently occur in chains. They 

 first two organisms liquefy gelatine very rapidly, but the 

 last does not. This last organism — the Photo-bacillus 

 Fluggeri — has the most marked phosphorescent power. 

 Beyerinck states that these organisms are best grown in 

 fish-broth made with sea- water, to which is added 1 per 

 cent, of glycerine, 0'25 per cent, of asparagin, and 8 per 

 cent, of gelatine. Several other varieties of light-giving 

 bacteria are known. They all, generally speaking, grow 

 best at a low temperature. 



Pink Torula {Saccharomyces rosaceus). — This organism is 

 very common in air, dust, etc. It is a slightly rounded or 

 oval yeast, the cells ranging from 5 to 8 /x in diameter, 

 which, under the microscope, are seen to contain a deli- 

 cate yellow pigment, but appear of a pink colour when 

 seen in the mass. Cultural characters : 



Gelatine Tubes. — Small white or grayish points are seen 

 along the line of inoculation, which afterwards gives rise 

 to a coral pink mass. 



Potatoes and Bread. — A bright coral pink growth forms. 



Bacillus Prodigiosus. — This organism is common in the 

 air, dust, etc. It is a very short bacillus, that differs 



