7f) A Bacterial Spot of Citrus 



The bacillus grew almost as luxuriantly under reduced pressure as 

 in the control tubes. In the absence of oxygen, i.e., practically in an 

 atmosphere of nitrogen, and in COg growth was comparatively very 

 slow and restrained. 



Temperature. The bacillus grows through a wide range of tempera- 

 ture, and very rapid multiplication takes place at all temperatures 

 from 25° C. to 38° C. The optimum temperature is 35° C. At 15— 

 18° C. the organism grows very slowly, and at 0° C. no clouding can 

 be observed in tubes of nutrient broth. The organism is not killed 

 by long exposures to this temperature, but rapidly clouded tubes trans- 

 ferred to a warmer temperature after 10 days. The upper limit for 

 growth is 43° C, broth is not clouded at 45° C. and the bacillus is 

 destroyed by several days exposure to this temperature. 



The thermal death point (in standard 10 c.c. tubes 10 minutes 

 exposure) is 62° C. ; dry on cover shps it is 110° C. 



Reaction of medium. The organism is not very sensitive to the reac- 

 tion of the medium and grows almost equally well in broth with reactions 

 of + 15 to + 25, the optimum however is about + 20 of Fuller's scale. 

 It grows through a wide range and can grow in a medium of fairly high 

 reaction if the acid used is malic, citric or tartaric. 



Toleration of NaCl. The percentage of salt which the organism can 

 tolerate is surprisingly high; some sUght growth took place in tubes 

 containing 10-5 per cent. NaCl and those w^th 10 per cent, were decidedly 



i 



clouded. Involution forms are however produced in broth containing f 



high percentages. 



Desiccation. A young agar culture was suspended in water and 

 smeared on cover sHps. As soon as the smear was dry, these were 

 transferred to a desiccator; they were removed from time to time and 

 dropped into tubes of nutrient broth. The organism was still alive 

 after 80 days, more prolonged tests have not yet been carried out. 



Sunlight. The test was carried out in very bright sunhght soon 

 after midday in the month of October. Thinly sown plates were 



