238 BACTERIA IN RELATION TO PLANT DISEASES. 



but did not spread far and soon dried out. A wilt spot also appeared on at least one of the 

 inoculated cotyledons (42). None of these infections led to any secondary signs. These 

 results were all it will be recalled with the cucumber strain of the bacillus. 



Inoculations of November 22, 1894. 



Nine small vines of crookneck summer-squash (Cucurbita sp.), 8 to 12 inches in height, 

 were inoculated by means of needle-pricks, using young pure-cultures of Bacillus irachei- 

 philus derived from three different plants (cucumber-strain) . Three vines were pricked on 

 one of the cotyledons, three on the blade of the first leaf, and three on the petiole of the 

 latter. All of these were growing rapidly at the time of the inoculation. None of the leaves 

 had reached their full size when pricked. Nos. 48, 49, and 50 were inoculated from tube 9, 

 November 12; Nos. 51, 52, and 53 were inoculated from tube 3, November 12; Nos. 54, 55, 

 and 56 were inoculated from tube 8, November 12. Tubes 9, 3, and 8 of November 12 were 

 white, sticky, wet-shining potato-cultures looking exactly alike. These three cultures were 

 derived from as many tubes of potato-broth which had been inoculated directly from the 

 interior of diseased vines. No. 9 was obtained from vine No. 33, No. 3 from vine No. 29, 

 and No. 8 from vine No. 25. 



(48.) One of the cotyledons was pricked. The twenty-first day both cotyledons were shriveled 

 but this came about naturally and was not the result of infection. Three months after inoculation 

 the vine was wholly dried up but there were no bacteria in the vessels or parenchyma of the stem. 

 Nos. 48, 49 and 50 were in the same pot. 



(49.) This vine was inoculated on the blade of the first leaf. The twenty-first day the cotyledons 

 had shriveled but there was no result from the inoculation. February 28, 1895, the vine was wholly 

 dried up. Examination showed the vessels and parenchyma of the stem to be free from bacteria. 



(50.) The petiole of the first leaf was inoculated. The twenty-first day the cotyledons had 

 shriveled. There was no result from the infection. Three months after inoculation the vine was 

 wholly dried up. It was examined under the microscope for bacteria but none were found, either 

 in the vessels or parenchyma of the stem. 



(51.) One of the cotyledons was pricked. The twenty-first day the cotyledon had shriveled 

 naturally, and not as a result of infection. February 6, the vine was drying up. It was now exam- 

 ined microscopically but there was no trace of bacteria in the stem. 



(52.) The blade of the first leaf was pricked. The cotyledons shriveled after a time and the vine 

 dried up but this happened naturally and not as a result of inoculation. The stem was examined 

 for bacteria on February 6, but none were found. 



(53.) The petiole of the first leaf was inoculated. There was no result from the pricks. The 

 cotyledons shriveled and the vine dried up after a time but the stem contained no trace of bacteria. 



(54.) One of the cotyledons was pricked. There was no result from the inoculation. Both 

 cotyledons shriveled and by February i, the vine had lost all its leaves and begun to shrivel. On 

 microscopic examination there was no trace of bacteria in the vessels. 



(55.) This was inoculated in the blade of the first leaf. The cotyledons shriveled and the vine 

 finally lost its leaves and began to shrivel but without any signs of the disease. There was no trace 

 of the bacteria in any of the vessels of the stem where thin sections were cut and examined under the 

 microscope. 



(56.) The petiole of the first leaf was inoculated. The behavior of this vine was like the pre- 

 ceding. It finally lost its leaves and began to shrivel but no trace of the wilt appeared. No bacteria 

 were found in the vessels. 



Remarks. — This result was unexpected and discouraging. The squashes grew from 

 seeds planted October 3 1 . The cultures used were ten days old. 



Inoculations of November 26, 1894. 



Four squash vines and one potato vine were inoculated in the hothouse with a 6-day 

 old culture of Bacillus tracheiphilus. A drop of sterile water was put on the surface of a 

 squash leaf and a little mass of the white, sticky, wet-shining, actively motile (just exam- 

 ined) bacillus put into it, stirred around and pricked in with a steel needle. Each leaf 

 received many punctures. The culture used (cucumber-strain) was slant potato No. 2, 



