172 Journal o f Agricultural Research v 0 i. xxix, No. 4 
below the growth becomes more trans¬ 
lucent. Tests show that the sugar has 
disappeared from this changed part 
of the medium but that the starch 
content is practically the same as in the 
controls. 
A very characteristic odor develops 
in cultures on this medium. It sug¬ 
gests ammonia, also hydrogen sul¬ 
phide, sauerkraut and fermenting fruits. 
Cultures kept on artificial media for 
long periods produce less odor and less 
brown color than recently isolated 
cultures. 
Starch agar.—T o ordinary peptone- 
beef agar 1 per cent of potato starch 
was added. Streaks were made on this 
medium and colonies also were grown 
by the usual p< mred-plate method. 
Growth was abundant and the mar¬ 
ginal growth was unusually wide, 5 to 
20 mm., and thin on both the streaks 
and colonies. After 10 days the plates 
were flooded with iodine potassium 
iodide. Seven isolations including the 
one selected as the type showed no dia- 
stasic action on the starch. One other 
isolation gave a very slight reaction. 
A medium of potato starch, dextrose 
and agar was tried but the organism 
produced on this very scanty growth. 
The medium just below the growth was 
tested and gave as strong a starch 
reaction as the control. 
Milk. —Inoculated milk forms a 
smooth, soft coagulum in 3 to 4 days. 
Clearing begins promptly and is com¬ 
plete within 2 weeks at temperatures 
30° to 33° C. (At temperatures 26° 
to 29° the digestion is somewhat 
slower.) The medium becomes pale 
yellow, translucent and very viscid. 
After some weeks the color deepens to 
light brown or deep cream. Reaction 
is at first acid, then alkaline. 
Litmus milk. —There is a slight, 
fugitive reddening which is likely to be 
overlooked unless cultures are closely 
watched. Reduction begins promptly 
and is complete in from 6 to 8 days. 
In 2 weeks or less the blue color begins 
to return and in 4 or 5 weeks the 
cultures are dark blue. 
Some puzzling crystals formed in 
milk cultures. In general they may be 
described as brittle, hollow spheres 1 
to 1.5 mm. in diameter; fairly smooth 
on the surface but not shining. A 
few were found hanging from the 
pelliclelike surface growth but most 
were on the surface of the sediment. 
Under microscopic examination the 
wall appears to be composed of minute 
crystals and some amorphous substance. 
They resist considerable pressure. If 
cut, the edges are fairly smooth. The 
interior cavity has a diameter about 
one-half that of the whole sphere. 
Water does not dissolve these crystals, 
neither does 10 per cent KOH so it 
would seem that they are not composed 
of sugar or casein. They dissolve in 
acetic acid, dilute hydrocholoric acid, 
and sulphuric acid. Alcohol, xylol, 
ether, acetone, chloroform, and am¬ 
monia had no effect. 
Litmus agars with sugar_ —Litmus 
agar with 1 per cent peptone and 1 per 
cent of dextrose, lactose, saccharose, 
maltose, galactose, mannit, or glycerin 
was used. Reddening occurred within 
24 hours in the dextrose and galactose. 
Lactose, mannit, maltose, saccharose, 
and glycerin showed slight reddening 
in 3 days. 
Fermentation tubes. —Fermenta¬ 
tion tubes containing 2 per cent Difco 
peptone and 2 per cent dextrose, 
saccharose, lactose, galactose, maltose, 
mannit, or glycerin produced abundant 
clouding and a pellicle in the open end. 
Dextrose and galactose gave most 
growth and in these there occurred a 
faint clouding after 12 days in the 
closed ends. No gas formed. 
Fermentation tubes containing sterile 
milk produced no gas. The milk 
cleared rapidly in the open end, fol- 
ldwed by slow clearing in the closed 
end. The reaction of the cleared milk 
was alkaline. 
Nitrate bouillon in fermentation 
tubes clouded well and formed a pel¬ 
licle in the open end within 2 days, 
and a faint clouding in the closed end 
was observed on the fifth day in one 
set of cultures and on the tenth day in 
another set. Ammonia was produced. 
Nitrates were not reduced. No gas was 
produced. 
Toleration of sodium chloride.— 
In peptone-beef bouillon containing 2 
per cent sodium chloride, the growth is 
practically normal. Growth becomes 
less in 3 per cent, very scanty in 
per cent, and in 4 per cent no growth 
occurred. 
Uschinsky's solution. —Thin uni¬ 
form clouding occurs in 24 hours. 
A pellicle forms. There is no color re¬ 
action except a trace of green in some 
cultures after 8 weeks. The medium 
becomes as viscid as egg albumen and 
with age and evaporation it is almost 
like rubber. 
Fermi's solution. —Growth is bet¬ 
ter in Fermi's solution than in Uschin¬ 
sky’s. Thin, membranous pellicles form 
repeatedly. As many as nine pellicles 
have formed in one culture tube. 
After 3 to 4 weeks the medium is pale 
yellowish green. Not viscid. 
Cohn’s solution. —Growth is slow 
at first but after a few days is about 
