214 



BACTERIAL DISEASES OF PLANTS 



various synthetic media; Cohn's solution, Uschinsky's solution, 

 Fermi's solution, Meyer's solution, etc. 



Non-nutritional Environment. — This organism offers a number 

 of very interesting problems. Perhaps you can help to settle 

 some of them. Can you get any growth in milk, or in bouillon, 

 at 1°C., or at 37°C. ? What is the thermal death-point? Deter- 

 mine its toleration for malic, citric, and tartaric acids begin- 



i 



Fig. 157. — Longitudinal section of a tomato leaf .showing bundle disorganiza- 

 tion due to Aplanobacter michiganense. Stained section from a sprayed leaf. 

 Time, 21 davs. 



ning with +20 (the acid of the tomato is said to be tartaric) ; for 

 sodium hydrate beginning with —20°. My own experiments 

 lead me to think it is rather tolerant of alkaU and compara- 

 tively sensitive to organic acids. Try salted bouillons — 1, 2, 3, 

 4, 5, etc., per cent. Determine if you can the inhibiting sub- 

 stance in the culture-media in which it makes such a slow growth; 



