92 



FRED W. TANNER 



Transfer to fresh media, however, gave good growth and much 

 pigment was produced. 



Burge and Neill (1915), in a paper on the comparative resis- 

 tance of fluorescent and non-fluorescent bacteria to ultra-violet 

 light, conclude that fluorescent bacteria are better able to resist 

 ultra-violet light than those which do not produce this pigment. 

 Their cultures of fluorescent bacteria were secured from among 

 those which form the basis of this investigation. Table 3 indi- 

 cates the results which they secured with the fluorescent bac- 

 teria. The numbers in parentheses are those which the cul- 

 tures bear in this paper; the other numbers are those which 

 Burge and Neill assigned to them. 



TABLE 3 

 Germicidal action of ultra violet light on fluorescent bacteria 



Million. 



This table indicates that these bacteria have a high resistance 

 to ultra-violet light. In order to secure some basis for compar- 

 ing this character, the same authors exposed such common 

 forms as B. coli {communis), Pseudomonas violacea, Sarcina lutea 

 and B. {proteus) vulgaris, which are not fluorescent, to the effects 

 of the ultra-violet light. In no case were any of these bacteria 

 able to resist the effects of the ultra-violet light for more than 

 200 seconds. Most of them could not survive an exposure of 



