426 BACTERIAL DISEASES OF PLANTS 



form-tolerant, sodium chlorid-tolerant (up to 3.5 per cent), 

 lab-producing, acid-forming (with certain sugars) rod-shaped 

 schizomycete, which grows on agar-poured plates in the form of 

 small circular, somewhat raised, wet-shining, translucent colo- 

 nies. Streaked on agar from agar the growth is smooth and 

 shining, but when streaked on agar from peptone bouillon the 

 various strains (daisy, hop, etc.) usually give a thin, wrinkled 

 and dull surface. On gelatin plates the surface colonies are 

 circular, small, dense, white and non-liquefying. In +15 pep- 

 tone bouillon after some days there is more or less pellicle and a 

 whitish rim of stringing, gelatinous threads ; earlier (48 hours) the 

 bouillon contains numerous delicate suspended filaments which 

 are best seen with oblique light and on shaking. In old undis- 

 turbed bouillon cultures there is a rather firm whitish pel- 

 licle and very little clouding of the fluid. There is a white 

 transient growth on steamed potato with some graying of the 

 substratum. Growth in Uschinsky's solution is scanty; in 

 Cohn's solution, scanty or absent. In milk the casein is thrown 

 out of solution but only after several days. Litmus milk is 

 blued (never reddened) and the litmus is frequently reduced. 

 The living organism takes up Congo Red from culture media 

 containing it and in this way may be distinguished from the 

 root-nodule organism of legumes (Karl Kellerman). Verified in 

 1919. Indol production, scanty. There is an invertase, and a 

 lab ferment. Some ammonia and hydrogen sulphide are pro- 

 duced. It grows from 0°C. to ±37°C. The optimum tempera- 

 ture for growth lies between 25° and 30°C. The thermal death- 

 point (10 minutes exposure in the water-bath in test tubes in 

 + 15 peptone beef bouillon) is approximately 51°C. It shows 

 slight toleration for organic acids (malic, citric, acetic) and still 



parison with 2. Spiral vessels at the left, pitted vessels at the right. (2) Longi- 

 tudinal section through a petiole showing tumor-strand in a bundle. Spiral 

 vessels at the left, pitted vessels at the right. (3) Cross-section of stem between 

 primary and secondary tumors, showing large-celled tumor-strand with big 

 nuclei. Pith below, inner wood above. Tumor-cells wedging apart the spiral 

 vessels. (4) Cross-section of a stem between tumors. Pith below, wood above; 

 in the center is a tumor-strand developing tracheids out of certain of its cells. 

 They contain nuclei and are still immature. The vessels above are the normal 

 spiral vessels of the inner wood. 



