WILT OF CUCURBITS. 27 1 



(290.) Common Watermelon. The ninth day there was wilt of the tip of the leaf beyond the 

 pricks and reaching down to them. There was only a slight change the following noon, and the 

 eleventh day the wilt seemed to have stopped. The tip of the leaf beyond the pricks was dead (a few 

 sq. mm.) but between them the tissue was still living, although a yellowish green color. Two days 

 later all but about one-twenty-fifth of the pricked leaf-blade was normal. There had been little 

 change since the eleventh day. The twenty-fourth day the wilted portion of the leaf was brown and 

 dry but there had been no increase of the disease. 



(291.) Cucumis erinaceus. The ninth day there was wilt in the pricked area but the remainder 

 of the leaf-blade was turgid. The following noon there was no change. The eleventh day there was 

 a small dead patch in the pricked portion, but no general wilt of the leaf. The terminal portion had 

 recovered its turgor. On April 17 the terminal one-sixth of the leaf in and beyond the pricked por- 

 tion was wilted, but the rest of the plant was normal. The twenty-fourth day the plant had recovered 

 and was growing. June 25 the plant had fully recovered and was making a fine growth. 



(292.) Cucumis erinaceus. The ninth day at 9 a.m. the terminal part of the pricked leaf-blade 

 had wilted and in the afternoon of the same day the wilt involved the whole leaf-blade. The follow- 

 ing day the blades of the two leaves next above and the two next below the pricked leaf had wilted. 

 The petioles were turgid. The eleventh day the wilt was but little if any worse than on the preceding 

 day and the petioles were still rigid. Two days later the blades of six leaves were badly wilted or 

 shriveled. The petioles were rigid and the terminal leaf and one or two at the base were normal. 

 The twenty-fourth day several leaves were dead but the plant as a whole seemed to be recovering 

 and had apparently thrown off the disease. The weather was cool. June 16 the plant had recov- 

 ered and had a good color but was a trifle stunted. June 25 the plant had entirely recovered and 

 was making a good growth. 



Remarks. Watermelon, Echinocystis lobata, and Melothria scabra developed only slight 

 local signs. In one vine of Cucumis erinaceus only slight local signs appeared. In another 

 vine of the same species, constitutional signs followed the local wilt, but finally the plant 

 threw off the disease and recovered. Cucumbers first showed local signs (in the pricked 

 parts) and then general signs ending in death. 



Inoculations of June 16, 1S96. 



Inoculations were made in the hothouse at 11 a. m., on Cucurbita foetidissima, Apodan- 

 thera undulata, Cucurbita pahnata (?), Cucurbita digitata, Trichosanlh.es cucumeroides, 

 Passiflora incarnata, Cucumis melo var. dudaim, Citrullus vulgaris, Echinocystis lobata, and 

 Cucumis erinaceus. All the plants were infected from culture No. 16, May 27, a tube of 

 peptone-water (cucumber-strain). This culture would have been old and exhausted long 

 before but for the fact that the organism made no growth in it for the first 16 days, having 

 been kept all of this time in the ice-box at temperatures ranging from 6 to io C. At 4 p. m., 

 June 12, it was removed from the ice-box and put at room-temperature (25 or 26 C). 

 In 48 hours it showed faint clouding and for the 36 hours preceding its use for inoculation 

 it had been well clouded with good rolling clouds on shaking. When examined in a hanging 

 drop the culture was seen to contain numerous rods in process of division. Some of the 

 bacteria were actively motile, darting ahead long distances ; others, slowly tumbling ; others, 

 stationary. There were a few involution forms. A copious quantity of the fluid was lifted 

 out on a sterile platinum loop, placed on the surface of a clean leaf and pricked in with a 

 sterile steel needle. The loop and needle were flamed after each operation and used again 

 as soon as cold. In most instances a second loop of the culture was rubbed over the numer- 

 ous delicate pricks. At the time of the inoculation the hothouse was cool, there was no 

 wind and the sky was overcast. There could not have been a better day nor apparently 

 a more suitable culture. 



(293.) Cucurbita foetidissima (grown from seeds of Tourney's second sending. Looks a 

 little different from the first sending, as if the plant were a variable one). Up to the ninth day no 

 signs had appeared, but 2 days later (1 p.m.) there was a very slight wilt of the pricked leaf at one 

 edge of the pricks. July 14 the plant was entirely dry-shriveled as a result of the inoculation. 



(294.) Cucurbita foetidissima. This plant must have contracted the disease as early as the fourtli 

 or fifth day. On the sixth day the blades of five leaves were wilted, i.e., that of the pricked leaf and 

 of two leaves above and two below. The seventh day the pricked leaf was wholly shriveled, the 



