A Bacterial Disease oe Alealea 2 7 
Pot No. 20. —Stem inoculated by needle pricks with culture oC Ps. 
medicaginis, n. sp. isolated from diseased stem. Sept 3rd. watery areas 
for 1 to 2 mm. around each needle prick and yellowish; Sept. <th. dar v 
brown; Sept. 30th. black. 
Pot No. 21. —Controls. One stem scarified with a sterile scalpel and a 
second pricked with a sterile needle. No change visible at any time m 
eithei stem. plant inoculations of November 2, 1909. 
Cultures used were isolated June 1, 1909. 
Pot No. 22. —Three stems were scarified and smeared with a cultu e 
of Ps. medicaginis, n. sp. isolated from an infected stem. On Nov. 7t L 
two of them were watery, shiny and yellow, while a liquid had been oozing 
from one and had dried on the stem. The third stem showed almost no 
change from the check. By Nov. 18th. all of the scraped areas were 
dark, watery green and turning brown; by Nov. 20th, they were a dark 
brown; a microscopic examination on Nov. 23rd. showed a typical 
fection. (See colored plate.) 
Pot No 23. —Two stems were inoculated by needle pricks with a 
culture of Ps. medicaginis, n. sp. isolated from a diseased stem; Nov- 7th, 
yellowish, watery appearance around each one of the stabs, Nov. lStti, 
needle pricks all taking well; very well defined brownish green areas one 
to two mm. around each; infection spreads slowly; No\. 20th. the a is 
eased spots dark brown and slightly sunken; Nov. 2 3rd. an examination 
of the diseased tissue gave milky cloud in the mount and swarms of germs 
under the microscope. (See colored plate.) 
Pot No. 24. —Stem inoculated by smearing culture of I s. medicaginis, 
n so upon* the unbroken epidermis. The object, here, was to attempt 
to secure a successful infection through the stomata. Nov. 10th two 
yellowish, watery spots developed on the part of the stem smeared; Now 
1 Stb these spots were dark brown and by Nov. -4th. they weie almost 
black. A subsequent microscopic examination showed a true bacterial 
infection. . . . . . r 
In order to eliminate the germicidal action of the dnect i ays 
of the sun, the plants were shaded by one thickness of canvas, 
placed next to the glass roof. . . . , 
In order to determine whether the infection was communicated 
to the plants through the roots, twelve pots were prepared with sick 
soil containing quantities of the diseased stems. Fifteen germin- 
ated alfalfa seeds, which had been sterilized previously m a 1-500 
mercuric chloride solution, were planted in each of the above pots. 
\ o-ood vigorous stand was obtained. The possibility ot frozen 
stems was eliminated by growing the alfalfa in the greenhouse and 
the danger from dust infection was reduced to a minimum by.keep¬ 
ing- the surface soil in the pots moist. These plants are now sixteen 
months old and up to the present time not a single stem 111 any ot 
the twelve pots has shown any sign of the disease. . From these 
results, we can say with a reasonable degree of certainty, that the 
disease is not. primarily, a root trouble, and if the roots do become 
diseased, the infection must start from the crown and work down- 
ward. 
SUMMARY OE GREENHOUSE EXPERIMENTS. 
From these experiments it will be seen, first, that we have 
been able to produce the disease successfully m ioo per cent of the 
