190 



BACTERIA IN RELATION TO PLANT DISEASES. 



September 30. Tobacco (24 plants) was inoculated by needle-pricks with beef-bouillon cultures A to D, September 

 20 (potato tuber from Hastings, Florida). 



October 26. Tomatoes (3 plants about 18 inches high) were inoculated with potato cultures Nos. i and 2, October 20 

 (growth black on the potato) ; alive October 23. The organism was not plated out, but descended from potato 

 cultures Nos. i and 2, October 19, which were streaked directly from diseased tuber from Portsmouth, Vir- 

 ginia. It was probably the right organism it showed the typical jet-black growth on potato. 

 Result. Failure. 



October 26. Tobacco plants were inoculated with same cultures used for above. 

 Result. Failure. 



October 28. Tobacco plants were inoculated with potato cultures Nos. 3 and 4, October 23 (from Portsmouth, Vir- 

 ginia, tuber); alive October 27. 

 Result. Failure. (For successful inoculations on tobacco see Wilt Diseases of Tobacco, p. 227.) 



October jo. Tomatoes (2 vines, 18 inches high), 

 were inoculated with potato culture No. 

 2, October 23 jet-black (from Ports- 

 mouth, Virginia, tuber). 

 Result. Failure. 



November 24. Tomatoes (5 vines) were inocu- 

 lated with potato cultures Nos. i to 5, 

 November 10, each from a separate 

 colony on plates of October 19 (potato 

 tuber, Portsmouth, Virginia). 

 Result. Failure. The cultures were alive; the 

 transfers made from them on date of 

 inoculation grew well. 



A single needle-prick introduc- 

 ing into a susceptible plant a small 

 quantity of a virulent culture is suffi- 

 cient to produce this disease, as shown 

 on plate 31, right-hand figure. 



MORBID ANATOMY. 

 The premature and excessive de- 

 velopment of roots on tomato shoots 

 as a result of this disease has been 

 mentioned under "Etiology." For a 

 section through such incipient roots, 

 showing their origin and relation to 

 infected tissues see fig. 98. An en- 

 larged view of bac- 

 teria from this section 

 is shown in fig. 99. 



In rapidly fatal 

 cases there are no 

 hyperplasias in con- 

 nection with this dis- 

 ease other than the 

 adventive roots on 



Fig. 98." 



tomato stems, but in stems of tomato and potato inoculated with feebly virulent cultures 

 there may be considerable enlargement in the vicinity of the punctures. Such stems 



*Fic. 98. Cross-section of a small portion of stem of tomato plant (No. 26) inoculated with Bacterium solana- 

 cearum on June 8, 1895, and fixed in strong alcohol on July 3. The figure shows vessels occupied, the formation of 

 small bacterial cavities, and a well-developed incipient root (R), the growth of which has been stimulated by the pres- 

 ence of the bacteria at a distance. Several much more rudimentary roots are depicted in the upper portion of the fig- 

 ure (R 1 ). At the left, above the lower cavity, the bacteria fill the intercellular spaces around a few cells (X). The bast 

 fibers are not distinct in the section itself, which was stained with special reference to the bacteria. There are no bac- 

 teria immediately under or in the budding root (R). Slide 1 1 1 (2. For further illustrations of these budding roots see 

 various plates. 



fFic. 99. Bacterium solanacearum from inoculated tomato plant No. 26, 1895. An optical plane from one of the 

 cavities shown in fig. 98. 





