388 BOTANICAL GAZETTE [DECEMBER 
Growth on gelatin—Grown on gelatin of standard composi- 
tion, liquefaction results and a green color is produced which 
gradually diffuses throughout the medium, the color being most 
intense near the surface. Generally after a few days a distinct 
red dichroism (fluorescence?) appears which increases with 
age.* 
For the production of the coloring matter in large amount 
the following method is employed. A 10 per cent. solution 
of gelatin is made nutrient by adding 1 per cent. peptone 
(Witte or Chaputeau) and is rendered distinctly alkaline with 
sodium hydroxid. The medium is then clarified as usual with 
white of egg. It is then sterilized in the steam sterilizer in 
the ordinary manner. Gelatin of from 8 to 30 per cent. con- 
taining I to 5 per cent. peptone gives almost equally good 
results. ; 
Since the coloring matter is formed only in the presence of 
an abundance of oxygen, cultures are made in large Fernbach 
flasks (antitoxin flasks) having a diameter of 20 to 25° at the bot- 
tom, the amount of gelatin added being sufficient to give a depth 
of about 1°%™ (about 200%). The rapid production of as large quan- 
tities of pigment as possible being the end in view, the culture 
flasks thus prepared are inoculated with 1 to 2° of the liquefied 
gelatin poured from a very active culture of known purity, and 
are then placed in a closet protected from the light, where they 
are kept at a temperature of from 15° to 20°C. If the temper 
ature rises much above 20° the production of pigment dimin- 
ishes, and ceases if the culture be placed in the incubator. This 
is true for all culture media; the best results are obtained when 
the cultures are kept cool. 
Fernbach flasks prepared as above begin to show at the end 
of 18 to 24 hours a decided green color which rapidly ne 
in intensity. At the end of three days the entire gelatin has 
assumed an intense, bright, grass-green, owing to the easy solu- 
bility of the pigment in water. Day by day the green — 
more intense and slowly darker, liquefaction also begins and wit 
‘For diagnostic details the reader is referred to the articles already mentioned. 
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