WILT OF CUCURBITS. 267 



(262.) Common gourd (No. 229 of December 3, now inoculated for the third time). Many 

 pricks were made on the blade of a leaf half-way up the stem. The ninth day there had been no wilt. 

 Up to March 4 there was no general wilt. 



(263.) Balsam apple (No. 230 of December 3, now inoculated for the third time). Many pricks 

 were made on a leaf half-way up. This was a small plant on December 3, when it was first inoculated 

 but now it was about 16 inches long with 17 leaves. The others had grown nearly as much. The 

 seventh day there was wilt around the pricks. This had appeared probably the day before. Two 

 days later the wilted area extended out a short distance from the pricked area. Up to March 4 

 (56 days) there had been no general wilt and the plant was still growing slowly. 



(264.) Balsam apple (No. 231 of December 3, now inoculated for the third time). Many 

 pricks were made on a bright green leaf half-way up the stem. The seventh day there was wilt 

 around the pricks which, however, increased little if any during the next 2 days. Up to March 4 

 there had been no general infection. Not even all of the pricked leaves wilted : They only became 

 somewhat yellowish. 



(265.) Balsam apple (No. 232 of December 3, now inoculated for the third time). Many pricks 

 were made on the blade of a bright green leaf growing midway of the stem. The seventh day there 

 was a wilted area around the pricks. Two days later there was little, if any, increase in this area. 

 On March 4 the plant was still healthy. 



(266.) Luff a acutangula (No. 235 of December 3, now inoculated for the third time). Many 

 pricks were made on a leaf -blade near the apex. On January 16 the plant was healthy. Up to 

 March 4 there was no general wilt. 



Remarks. Cow-pea, tobacco, and Luffa refused to take the disease. Pumpkin, squash, 

 balsam-apple, and gourd showed local signs but even the pricked leaves did not succumb as 

 a whole and no secondary or general signs appeared, i. e., there was no wilt outside of the 

 pricked leaf except perhaps in Nos. 255 and 256. Cucumber (No. 251) contracted the 

 disease. 



INOCULATIONS OF JANUARY 21, 1896. 



Inoculations were made in the hothouse at 10 a. m., on Cucumis sativus, Cucurbita 

 calif ornica and Cucumis anguria. The bacillus was taken from tube 6 December 31, the 

 bulk of which had been used up the preceding day in inoculating fermentation-tubes and 

 making new agar-cultures. The bacteria were introduced by needle-pricks. The plants 

 were under observation until March 4. 



(267 and 268.) Cucumis sativus. These were old vines. Many pricks were made on a leaf-blade. 

 No signs appeared. 



(269.) Cucurbita californica. Many pricks were made in the fourth leaf-blade above the 

 cotyledons. The vine was a young one. 

 There was no result from the inoculation. 



(270 and 271.) Young Cucumis anguria. Many pricks were made on a leaf-blade. 

 There was no result from the inoculation on either plant. 



Remarks. These five inoculations were made into plants of three susceptible species. 

 All failed. The reason for this failure is to be sought in the nature of the culture used. 

 What was then puzzling is now perfectly plain. The culture was 21 days old, and was on 

 stock 93 b, an agar to which sugar had been added. On the same date as these plant inocula- 

 tions, four fermentation-tubes were inoculated copiously from the same culture and all 

 failed (7 days test) showing that the culture was dead. The body of the fluid in these 

 tubes consisted of slightly alkaline (litmus) peptonized beef-broth free from muscle-sugar. 

 One of these fermentation tubes contained saccharose, another maltose, another lactose 

 and the fourth dextrine, each of these very suitable foods being added in the proportion of 

 0.2 per cent. The early death of the culture was undoubtedly due to the injurious action of 

 its own by-products, i. e., of acids derived from the decomposition of the sugar, this 

 organism being extremely sensitive to acids. 



