150 STORRS AGRICULTURAL EXPERIMENT STATION. 
Potato.—Spreading, thin, contoured, white, moist, luxuriant; potato dis- 
colored. 
Grows better at 20° than at 37° Aerobic. 
THE GENUS PSEUDOMONAS. 
I. Non-liquefying. 
Ps. lactis Middletownii n. s. A Pseudomonas, producing gas, but no acidity, 
Morphology.—Size, 1.4.x .8u-.94. No chains, no spores, no capsules. 
Gram stain negative. 
Gelatine colony.—A round, raised, smooth, gyrose, entire, gray-white colony. 
On “litmus gelatine the colony is coarsely granular, looking like a colony of 
yeast. 
Gelatine stab.—A dry pit is formed, with needle growth. 
Agar streak.—Filiform or spreading, smooth, thin, gray-white, moderately 
luxuriant, moist. 
Fermentation tubes.—No acidity in any sugar bouillon, but closed arm growth 
and gas produced in all. 
Bouillon.—A sediment, turbidity and a pellicle. 
Milk.—Rendered acid and curdled after several days, and subsequently 
slightly digested. 
Potato,—A \uxuriant, spreading, thick, gray-white growth; potato discolored. 
Grows at 20°, but hardly at all at 37°. Aerobic, or facultative anaerobic. 
Ps. fluorescens aurea Weigmann. A fluorescent, non-liguefying Pseudo- 
monas. This culture was sent me by Weigmann, but ‘had lost its fluorescent 
character when received by us. Its characteristics, as given below, were made 
in our laboratory. This is perhaps Ps. convexa of Wright. We have several 
times found a similar organism in milk, but unfortunately at the time we did 
not make a study of their flagella; but we have no doubt that they belong 
with this organism of Weigmann. We list one of our own organisms as 
variety A. 
Morphology.—Size, 2.5@x.9gu. Short chains. There are no spores nor 
capsules and the organism does not accept the Gram stain. [Our organisms 
were usually shorter. | 
Gelatine colony.—A round, raised, contoured, grumose colony, of a brownish- 
red color. [A green halo around the colony iscommon.] On Atmus gelatine 
it is much folded. 
Gelatine stab.—A filiform, needle growth and a raised, surface growth. [The 
surface growth is thick, and the gelatine may show a green color. | 
Agar streak.—A filiform, smooth, thin growth of a yellowish color, moder- 
ately luxuriant. It was probably originally fluorescent, but this character has 
been lost. Our own cultures always showed the fluorescence. 
Fermentation tubes.—No acidity, gas, nor closed arm growth in any sugar 
bouillon. 
