218 BACTERIA IN RELATION TO PLANT DISEASES. 
(4.) August 30, a young squash-fruit was punctured in 4o places and many germs thrust in 
from several of the white colony-like bacterial beads on cut stems. The fruit oozed juice profusely. 
September 6: Squash still sound externally. On making sections through the flesh it looks water- 
soaked around the stabs for a breadth of nearly a millimeter. It is not rotten. Placed in moist air 
under a dish there is a moist sticky ooze from these water-soaked parts; not white; no ooze from 
other parts. 
(5.) September 1: A leaf 7 inches across was wet on the upper surface over a square inch and a 
large white bacterial bead from the cut stem stirred up and pricked in with a needle. The leaf was 
then doubled together and inserted in a glass fruit jar (moist inside) and left 24 hours, the mouth 
being plugged with damp cotton wool (a defective method). September 2: Removed. No result 
where the germs were pricked in, but a sun-burn has appeared on the other half of the leaf. Septem- 
ber 11, 10 a. m.: Two small wilted spots have appeared on the area which was pricked ten days ago; 
6 p. m.: Spots have enlarged, each being about three-quarters of an inch long (each side of a vein) 
and not over one-fourth inch wide. ‘The petiole of this leaf is 6 inches long and all leaves on the axis 
above and below are healthy. 
(6.) September 1: A vigorous terminal shoot was enclosed in a large glass jar (wet inside and 
plugged with damp cotton wool), two leaves 3 or 4 inches wide, being first wet and several white 
masses of the bacterial ooze stirred into the water and then pricked in with a needle. September 2: 
Both infected leaves have blighted one-third to two-thirds and three others which touched them 
also show it. The blight includes the veins. These leaves are much younger and tenderer than in 
Experiment 5 (all probably due to sun-burn). September 11: Solely sun-burn. 
(7.) Two ends of a vigorous squash vine were put into a wet glass can, two leaves on each being 
infected with bacteria brought from Washington. This growth was wrinkled, dirty Isabella color 
[the wrong organism]. The bacteria were teased up in water on the leaf and pricked in with a needle; 
two more were infected in the same way from another block of potato in the same Petri dish. Mouth 
of can was closed with cotton and wet rags. All 4 leaves blighted in 24 hours, but probably all was 
due to sun-burn. September 11: Solely sun-burn. No colonies appeared on cut ends of stem or 
petioles which were yellowing. 
(8.) Some germs from the potato cultures [wrinkled dirty organism] were inserted into 2 green 
tomatoes and into the stem very thoroughly with needles. September 11: Tomatoes rotted slowly. 
Stem turned dark around puncture 1 mm. or more on outside and germs evidently infiltrated some 
distance into the tissue. My father afterwards picked and threw away the tomatoes for rotted, not 
knowing that I had inoculated them. 
(9.) Germs from the very gelatinous Isabella-colored, wrinkled, colony [wrong organism] on 
potato were rubbed up in well-water and pricked into the parenchyma and veins of four large turgid 
squash leaves, both sides, pretty thoroughly, with a cambric needle on September 7, 11 a. m. 
Leaves several feet from ends, and marked with twine. No results. 
(10.) September 7: The two turgid leaves (two different vines) which had bacteria pricked into 
them August 30, from the white ooze on cut squash-stems (see No. 3) are now badly wilted, while all 
the leaves to either side are turgid. These leaves are about 18 inches from the growing ends of the 
vines. I first detected the wilt yesterday morning (September 6), 7.e., about 8 days after the infection. 
They looked all right for 5 or 6 days and I had abandoned the experiments as hopeless and did not 
look at them for 2 days. The wilt to-day (September 7, 11 a. m.) is very decided and I can attribute 
it to nothing but the slow growth of the inserted germs. I now know all of the other supposed 
infections (7. e., those obtained in moist air in 24 hours inside of glass jars) to be due in great part at 
least, and probably altogether, to sun scald. This was determined by getting the same results 
without use of germs. ‘The cans rested on hot sand and the air became very hot inside and was 
saturated or nearly so with vapor of water.* September 10: The two squash leaves wilted completely 
but slowly, and are now crisp dry. ‘The petioles are still green and turgid, but one seems a trifle flaccid 
at the extreme tip although not yet shrunken or discolored. This one was cut away and divided into 
0.75-inch segments, and put on end in moist air. Two hours later there were plain indications of 
bacterial ooze from the cut bundles on some of the segments, and at 6 p. m., 7. e., in 7 hours, all of the 
segments had each several beautifully distinct milk white bacterial beads resembling colonies. This 
was true even of the segments cut 3 or 4 inches below the blade of the leaf. This sets at rest all 
doubt regarding the possibility of inducing the disease by pricking in the bacteria taken fresh from 
the cut stems. September 11, 6 p. m.: Leaves to each side of these two are still perfectly healthy and 
no similar case of natural wilt at end of vines has appeared on any of the vines during the time I 
have been here. There is no shadow of doubt now as to what caused these leaves to blight. The 
striking thing is [was to me at that time] that the blight should have taken 8 days to develop. Only 
*Defective technique. 
