WILT OF CUCURBITS. 237 



was still doubtful. The eleventh day the pricked cotyledon was the only one out of more than a 

 hundred which showed any yellowing. The following day the yellowing cotyledon exhibited a char- 

 acteristic, wilted place in the yellow pricked area. This was about 1.5 cm. long and 8 mm. wide. 

 The disease was progressing very slowly. The twenty-sixth day the pricked cotyledon had wholly 

 shriveled. February 28 the vine was wholly dried out but no bacilli were found in the vessels or 

 parenchyma of the stem. 



(43.) Hubbard Squash. The first true leaf was pricked many times and inoculated with a 

 white, sticky, wet-shining bacillus from potato-culture No. i, November 12. The eighth day an 

 irregular area including about 2 sq.cm. at the tip of the blade of the pricked leaf had wilted and 

 changed to a light dull-green color. Certain pricks were inside of the wilted area. The following 

 morning the wilted area had enlarged only a very little. The eleventh day the wilt was progressing 

 very slowly. There was scarcely a larger area invaded than 3 days before. The twenty-sixth day 

 the small wilted place first discovered had been dried up and brown for a long time. The disease 

 had not spread. Six days later the leaf was brought into the laboratory and the portion which 

 had wilted was put into alcohol. February 28 the vine had all dried out except the stem which was 

 yellowish green and flabby. No bacilli were found either in the vessels or in the parenchyma of the 

 stem. 



(44.) Hubbard Squash. One of the green cotyledons was pricked and inoculated with bacteria 

 from the potato-broth-culture of November 15. This was a pure culture and was actively motile 

 on November 16 at noon. The eighth day no signs had appeared. The twenty-sixth day the pricked 

 cotyledon was wholly shriveled. February 28 the vine was dried out completely. There were no 

 bacilli in the vessels of the stem. The same day that this plant was inoculated, loops from the potato- 

 broth of November 15 were transferred to other sterile potato-broths to see if the organism would 

 grow. In 4 days there was typical clouding in these tubes. 



(45.) Hubbard Squash. The first true leaf was pricked and infected from the potato-broth- 

 culture of November 15. The eighth day an irregular patch including about i sq.cm. had wilted and 

 changed to a lighter, dull-green color. This was on the margin of the leaf about 3 cm. to one side of 

 the midrib. It included some of the pricks. The eleventh day the wilt was progressing very slowly. 

 The invaded area was scarcely larger than 3 days before. The twenty-sixth day the pricked leaf was 

 yellow and flabby on one side. Six days later the wilted portion was brown and dry. The disease 

 appeared and dried out without spreading. The leaf was brought into the laboratory and the 

 diseased portion put into alcohol. February 28 (one-hundred and third day) the vine had dried out 

 with the exception of the stem which was still yellowish green and flabby. There were no bacilli in 

 the vessels of the stem. 



(46.) Hubbard Squash. One of the green cotyledons was pricked and inoculated from a thin, 

 white, wet-shining growth on slant agar (tube 12, October 28 from i, October 23). The eighth day 

 there were no signs of the wilt. The twelfth day the pricked cotyledon was slightly yellow at the 

 apex. The twenty-sixth day the pricked cotyledon was wholly shriveled. On January 26, (2 months 

 after inoculation) the vine was stunted and had lost all of the lower leaves, probably because it was 

 still in a 4-inch pot. The upper ones were green but small. The vine was brought into the laboratory 

 and its stem was examined but no bacilli were found either in the vessels or parenchyma. 



(47.) Hubbard Squash. Bacilli from a thin, white, wet-shining growth on slant agar (No. 12, 

 October 28 from i, October 23) were pricked into the first true leaf. The afternoon of the eighth day 

 a small area of the pricked part of the blade looked wilted but it was somewhat doubtful. The next 

 morning it was turgid. The vine was growing rapidly and was four times as large as when the 

 bacteria were pricked into it. The eleventh day the leaf showed a very slight change of color in the 

 middle of the pricked area, but I was doubtful whether this was the true wilt. In a day or two 

 there was a tiny place radiating from the pricks (3X8 mm.) which was unquestionably wilted. The 

 twenty-sixth day the disease had not spread. The thirty-second day the wilted spot was brown 

 and dry. The disease had appeared and then dried up. It had not spread at all. The small 

 spot was put into alcohol for future examination. On January 26 the vine was stunted and had 

 lost all of the lower leaves. It was still in a 4-inch pot. The upper leaves were green but small. 

 The stem was now examined but no bacilli were found either in the vessels or the parenchyma. 



Remarks The evidence derived from the inoculated tomato tends to show that the 

 bacterial wilt of cucurbits is distinct from that of tomatoes, especially since 8 muskmelon 

 plants and i cucumber plant inoculated on January 3 from the same culture as that used 

 for the fourth inoculation of the tomato promptly contracted the disease. 



The inoculated squash-leaves doubled in size between November 17 and November 22. 

 On vines 43, 45, and 47 wilt spots appeared after a time in the inoculated part of the leaves, 



