346 WATER BACTERIOLOGY 



Jordan studied 543 strains of bacteria from the Illinois, Missouri 

 and Mississippi Rivers and grouped them into the following classes, 

 depending upon their biochemical properties: 

 I. B. coli communis. 

 II. B. lactis aerogenes. 



III. B. proteus. 



IV. B. enteritidis. 



V. B. fluorescens liquefaciens. 

 VI. B. fluorescens non-liquefaciens. 

 VII. B. subtilis. 



VIII. Non-gas formers, non-fluorescent, non-sporeforrning bac- 

 teria which liquefy gelatin and acidify milk. 

 IX. Similar to Group VIII, save that milk is rendered alkaline. 

 X. Similar to Group VIII, save that gelatin is liquefied. 

 XL Similar to Group IX, save that gelatin is not liquefied. 

 XII. Similar to Group XI, save that the reaction of milk is not 

 altered. 



XIII. Chromogenic bacteria not included above. 



XIV. Chromogenic staphylococci. 

 XV. Non-chromogenic staphylococci. 



XVI. Sarcinse. 



XVII. Streptococci. 



The natural water flora are saprophytes and the most important 

 members found were: 



Group V (B. fluorescens liquefaciens} is probably more often 

 found in water than any other species. It liquefies gelatin and 

 produces a green fluorescence. 



Group VI (B. fluorescens non-liquefaciens') produces colonies with 

 a fluorescent shimmer and does not liquefy gelatin. They are 

 often very abundant in river water. 



Group VIII : Organisms which liquefy gelatin and acidify milk. 

 These are closely related to the proteus group and some of them 

 are B. liquefaciens, B. punctatus, B. circulans. These are found 

 more commonly at some seasons than at others. 



Groups XIII and XIV: Chromogenic bacilli and cocci. The 

 red-pigmented B. prodigiosus belongs to this type, as does also B. 

 ruber, B. indicus, B. rubescens and B. rubefaciens. Those pro- 

 ducing a yellow or orange pigment and belonging to this group are 

 B. aquatilis, B. ochraceus, B. aurantiacus, B. fulvus. At times 

 there occur organisms which produce violet-pigment B. molaceus. 

 The chromogenic cocci occurring in water are not so numerous; 

 of these, Sarcina lutea is the most common species. The non- 

 chromogenic cocci, which Jordan classes as Group XV, are more 

 numerous. 



Soil Bacteria. The flood waters are continually carrying to the 

 surface waters soil organisms, so we may at times find any of 



