264 
Journal of Agricultural Research 
Vol. XXVIII, No. 3 
house infection. It was a cool cloudy day with threat of rain and the plants 
were left uncovered. They were sprayed with the organism on two successive 
cloudy days, and then a three days’ continuous rain set in. Nine days after the 
first spraying the leaves were thickly speckled with infections, especially those 
inoculated from one colony, individual spots being as much as 2 mm. wide and 
some confluent areas as large as 1 cm. across. These spots were black, sur¬ 
rounded by yellow areas on some leaves while on others (older mature stem 
leaves) no yellowing occurred. Poured plates from such spots gave pure cul¬ 
tures of the white organism used for inoculation. The weather then turn" ~ Jl “ 
very warm, the spots did not increase materially in size and later atten>^ened. 
inoculation failed, both with reisolations from these leafspots and A copious 
colonies used to produce them. It seems evident that climatic c^'^ e ^ s * After 3 
cold and moisture, play a large part in the success of inocuM^ate has become 
peratures inhibit, and moist cool conditions greatly favo r 
the disease. - second day and is com- 
During April and May, 1923, several sets of in' 
doors on delphinium plants that had wintered, within 4 or 5 days and increases 
1921 which had produced the infections are moderately clouded. After 3 months’ 
tions of 1922 were used. AUko of white precipitate in the bottom of the tube 
with numerous small crystals. 
Uschinsky’s solution. —Within 24 hours a faint clouding may be seen in the 
upper part of the culture. By the second day a delicate pellicle has formed with 
blue-fluorescence just below it in the upper 2 or 3 mm. and by the fifth day 
clouding is heavy with a heavy pellicle and green fluorescence throughout. A 
heavy white precipitate is formed. 
Fermi’s solution. —There is prompt growth in Fermi’s solution with a beauti¬ 
ful blue fluorescence sometimes becoming green but more often remaining blue 
though held for several weeks. A heavy wrinkled pellicle is formed which does 
not fall readily on shaking, but clouding usually remains weak. Thumm * 7 states 
that all of the colors produced by fluorescent bacteria are due to the same pig¬ 
ment, the blue becoming green with the production of alkali by the organism. 
The addition of dilute ammonia to blue cultures of Bad. delphinii in Fermi’s 
solution turned them a vivid green. Blue and green cultures were tested for 
relative acidity with the following results: 
Blue Ph 6-5 or +41. 
Green Ph 6.6 or +34. 
Nitrate reduction. —Nitrate is not reduced. Tests were made with nitrate 
bouillon cultures 5 days old and 10 days old in which moderate clouding had taken 
place, using the starch-iodin-sulphuric acid test. 
Nitrogen compounds. —The ability of the organism to obtain its nitrogen from 
various nitrogen compounds was tested in 1 per cent water solutions of the fol¬ 
lowing: peptone, asparagin, asparagin plus dextrose, ammonium citrate, am¬ 
monium tartrate and ammonium succinate. The results are shown in Table I. 
• Ridgway, R. color standards and color nomenclature, pi. 15. Washington, D. 0. 1912. 
7 thumm, K. beitrage zur biologie der fluorescierenden bakterien. Arb. Bakt. Inst. Tech. 
Hochschule Karlsruhe 1: 291-377. 1897. Abstract in Smith, E. F. Bacteria in relation to plant diseases. 
1:238. 1905. 
