26 BOTANICAL GAZETTE | JANUARY 
Ammonium /artrate solution afforded one of the most inter- 
esting examples of a difference between the cultures employed. 
B. ft. albus produced a rich coloration of the medium within the 
space of twenty-four hours. On the tenth day B. 77. tenuis like- 
wise showed a slight tinge of color, and this slowly but steadily 
deepened, until, on the twenty-fifth day after inoculation, the 
color was as decided as in the tubes of B. 77. albus. None of the 
other species showed the slightest development of pigment, 
although a marked turbidity manifested itself in the tube inocu- 
lated with B. ff. hquefaciens, and a perceptible cloudiness 
appeared in the culture of B. ff. mesentericus and B. fl. putridus. 
The difference in the behavior of the several species in this 
solution was so striking that I repeated the experiment several 
times, always, however, with the same outcome. It is interesting — 
to note in this connection that Thumm * states that the only spe- 
cies (among B. ff. albus, tenuis, erythrosporus, putridus, and viridans) 
that was able to produce fluorescent pigment in a tartrate solu- 
tion (ammonium tartrate 0.5 per cent., potassium phosphate 0.05 
per cent., magnesium sulfate 0.01 per cent., calcium chlorid 
0.005 per cent.) was the one bearing the name of B. fl. albus. 
Thumm gives no description whatever of the various “ species” 
that he used, but they were probably derived from the same 
Sources as my own cultures. Thumm’s culture of ‘B. fl. tenuis” 
is recorded (p. 84) as showing “slight turbidity: no production 
of pigment” in the tartrate solution, while my culture designated : 
by the same name is able to form a notable quantity of pigment, 
although more tardily than B. fit. albus. In ammonium urate 
solution (urate 0.05 per cent.,° sodium phosphate 0.1 per cent. 
maghesium sulfate 0.1 per cent.), B. 72. Lgquefaciens produces 
pigment more rapidly than the other species, but at the end of 
seven days B. ff. mesentericus and B. fi. tenuis rival it in intensity, 
and after eighteen days growth BZ. fi. albus shows quite as deep 
a color as the species already named. There is at this time the 
5 Of. cit. p. 84. 
6 - . i 
*° On account of the comparatively slight solubility of the urate a smaller quantity 
was used than of the more soluble ammonium salts : 
