384 



MICRO-ORGANISMS IN WATER 



sodium sulphate. Some of the results already obtained 

 are given in the following table : 



Action of Sunshine on Anthrax Spores suspended in Water 

 (Percy Frankland) 



Thus the bactericidal action of light is very con- 

 siderably greater in water containing common salt than 

 in distilled water ; whilst, on the other hand, the addi- 

 tion of sodium sulphate in the same proportions has 

 little or no influence in this respect. An addition of 

 10 per cent, of salt appears to exercise even some 

 bactericidal effect in the dark. The action of this 

 material in enhancing the bactericidal action of light 

 is still more conspicuously brought out in the following 

 experiments : 



Action of Sunshine on Anthrax Spores suspended in Water 

 (Percy Frankland) 



Spores produced at 18-20 C. 



Sunshine. Number per c.c. 



I I I I 



No 1% 3% 10% 



additions NaCl NaCl NaCl 



4 hours 16,000 14,000 8,000 5,000 



11 hours 12,000 8,000 3,000 485 



21 hours 378 39 49 



Darkness. Number per c.c. 



I ~r i 



No 1 % 3 % 10 % 



additions NaCl NaCl NaCl 



13,000 13,000 9,000 12,000 



15,000 13,000 16,000 14,000 



18,000 15,000 14,000 9,000 



