468 Journal of Agricultural Research voi.v. No. 11 



Five days later, water-soaked spots appeared on the leaves, and by 

 November 3 there were typical browned spots on plants inoculated with 

 each of the three colonies. These spots swarmed with bacteria. Poured 

 plates on agar gave pure cultures of the same white organism. No further 

 inoculations were made until April 30, 191 5, when sprayings were again 

 made in cages as before, using subcultures of colony No. i , plated from 

 a spot produced by the inoculations of October 26. The plants used in 

 this case were of a common field variety and rather stunted but with 

 sound leaves. Three days after the first spraying water-soaked spots 

 appeared on the lower surface of the leaves, and by May 6 these had 

 enlarged into the typical angular, dry, brown spots. 



Another experiment on May 6, 191 5, using perfectly healthy, free- 

 growing Arlington white spine cucumber plants and subcultures from the 

 same colony (No. i) gave striking results. Several leaves showed tiny 

 water-soaked areas on the second day, and all the leaves were typically 

 and badly spotted by the sixth or seventh day. In this stage the spots 

 were one-fourth to three-fourths of an inch in diameter, angular, following 

 the larger veins, and water-soaked (translucent), not dry. In the early 

 morning drops of moisture (exudate) swarming with bacteria were found 

 hanging on the lower surface of such spots (PL XLV, fig. i). Pure 

 cultures of the causal organism were obtained by plating from one of these 

 drops. On the following day, or even later on the same day, white 

 films (bacterial crusts) replaced the drops (PI. XLIU, fig. i). The appear- 

 ance of infected leaves at the end of 12 to 14 days, when the diseased 

 areas have become dry and begin to drop out, is shown in Plate XIvIII, 

 figure 2. 



As the young unsprayed leaves developed on these plants, they 

 became naturally infected; and in three cases the stems and petioles of 

 this young growth also became water-soaked, exuded drops of fluid 

 (PI. XLIV, X, X), and finally broke or bent over (PI. XLV, fig. 2), ending 

 the growth of the plant. The cracking open of stems in this stage of the 

 disease is shown at X in Plate XLV, figure 2 , and in detail in Plate XLV, 

 figure 3. 



On the green fruits up to the end of August, 191 5, the writers were 

 able, with one exception, to obtain -v^ithin a week or 10 days (shipping 

 time) only a local infection and a bacterial exudate such as that shown in 

 Plate XLVI, figure i — no general soft-rot. Even when the fruit (PI. 

 XLVI, fig. i) was kept for another week at high temperatures (28° to 32° 

 C), it did not rot (PI. XLVI, fig. 2). Altogether 15 such fruits were 

 inoculated with virulent cultures, some on the vines and others in damp 

 chambers. 



Soft-rot occurred twice in young fruits (two-thirds grown) when placed 

 in damp chambers after inoculation. In the first case (the exception 

 referred to above), plates were poured from the soft interior of the one 

 fruit thus affected. As only spreading fimbriate colonies were obtained, 

 the soft-rot was attributed to an intruder, and no further studies were 



