24 BOTANICAL GAZETTE [JANUARY 
magnesium, or potassium) be added to the asparagin-phosphate | 
solution, abundant multiplication takes place together with a 
rich development of the fluorescent pigment. 
To determine the amount of sulfate necessary for the pro- 
duction of the pigment, solutions were prepared containing 0.2 
per cent. asparagin; 0.1 per cent. neutral sodium phosphate ; 
and respectively 0.1, 0.01, 0.001, 0.0001, and 0.00001 per cent. 
magnesium sulfate. All of the species except B. fl. putridus 
produced pigment in the presence of 0.01 per cent. and 0.001 
per cent. sulfate nearly as well as when 0.1 per cent. was used; 
with the smaller amount of sulfate, the development of pigment 
was slower, but the final result almost as intense, With 0.0001 
per cent. of sulfate a good development of color was brought 
about by all five species. In the presence of 0.00001 per cent. 
of sulfate B. viridans alone showed any well-defined development 
of pigment. There was the merest trace of color in B. ff. mesen- 
tericus, and the others were entirely without a tinge. 
The nature of the base associated with the phosphorus and 
sulfur appears to be a matter of complete indifference. Sodium, 
potassium, and magnesium salts gave similar results in whatever 
way they were combined. Even if ammonium phosphate and 
ammonium sulfate be used together, fluorescence appears, but 
it is somewhat less intense than in the presence of one of the 
bases mentioned above. . 
To determine the amount of phosphate necessary for the 
formation of pigment, solutions of 0.2 per cent. asparagin, 0.1 
per cent. magnesium sulfate, and varying quantities of neutral 
sodium phosphate were inoculated in the usual manner, In the 
asparagin-sulfate solution containing 0.001 per cent. of the 
phosphate, good color was developed by all the species, being 
deepest in the cultures of B. viridans and B. fl. mesentericus. In 
the same solution containing 0.0001 per cent. of phosphate no 
pigment was developed by any of the species; the turbidity 
was, however, slightly more pronounced than in the control 
tubes of simple asparagin-sulfate solution. 
These organisms are able to produce the fluorescent pigment 
