364 
Journal of Agricultural Research voi. xxiu. no. 5 
markings in the interior; there is no zoning, but a marginal ring occurs 
on some colonies after they are up several days. Colonies are 2 to 4 mm. 
in diameter. The agar does not change color. (Unlike the Lewis 
organism.) 
Agar stroke. —In 2 days there is a translucent wet shining rather thin 
growth on +13 peptone-beef infusion agar. In 3 days the growth is 
cream colored with undulating surface. There is no green color in the 
agar or condensation water. The surface is finely pitted at 4 days; 
crystals form in from 2 to 10 days. There is no viscidity until cultures 
are 1 month old or older, but even then there is no green color. (The 
Lewis organism produces a green pigment.) 
Glucose agar stab. —This is a favorable medium. Growth is fairly 
rapid and abundant on the surface of the stab; scant along the line of 
puncture. The color of 4-day-old cultures is Ridgway's Naples yellow,® 
and this is a deeper color than the growth on plain beef agar. (Same as 
the Lewis organism.) 
Lactose agar stab. —In this medium there is growth with abundant 
crystals. No green color. (The Lewis organism produces a green color.) 
Steamed potato cylinders. —A thin yellow growth occurs on the 
potato in 24 hours. In 2 days it is a Naples yellow; in 3 days the 
potato begins to darken a little, but there is no green fluorescence. The 
potato cylinders are still firm after a month. The starch in the cultures 
gives a purple reaction when tested with iodin in potassium iodid. 
(Lewis's organism produces a green fluorescent pigment after 48 hours.) 
Steamed coconut. —A thin faintly yellow growth occurs in 2 days on 
pieces of coconut steamed in tubes. Growth takes place in the water 
also but is not a yellow color. In 2 weeks the growth on the surface of 
the coconut is still thin and not viscid. (The Lewis organism produces 
a viscid growth on this medium.) 
Litmus milk. —There is a trace of clearing (whey) in 3 days but no 
color change. In 6 days there is a faint bluing in bands and a clearing 
at the surface for nearly 1 cm., but no coagulation. In from 10 to 15 
days the bands of color are faint and clearing has taken place in from 
one-half to the entire tube. Then it is a reddish blue color, dark hyssop 
violet, according to Ridgway. (With Lewis's organism the liquid is all 
a clear yellowish color in 8 days.) 
Sterile milk. —No clearing occurs before 5 days even at the optimum 
temperature of 26° to 28° C. At that time there is a ring of whey, cream 
colored, 3 to 5 mm. deep. Coagulation comes soon after the clearing 
appears; the curd is soft. There is no color change. Tested at 17 days 
the hydrogen-ion concentration expressed in P H value is 6.4 (Brom 
cresol purple). In 30 days over half the curd has been digested. (The 
Lewis organism does not coagulate sterile milk; it produces green fluores¬ 
cence with age.) 
Dunham's solution. —There is heavy clouding in this medium in 48 
hours, but not any marked difference from peptone bouillon. (Like the 
Lewis organism.) 
Peptone bouillon. —The organism clouds peptone beef infusion 
bouillon + 10 to +15 in 24 hours at a temperature of 23 0 to 27 0 C., when 
transfers are made from a young fluid culture. At 18 0 to 20° it is not 
clouded until 48 hours. Clouding is heavy in 2 days at 27 0 . Pseudo- 
8 Ridgway, Robert. Color standards and color nomenclature. 43 P-, 53 col. pi. Washington, 
D. C. 1912. 
