470 Journal of Agricultural Research VoI.v.no. n 



MORPHOLOGY AND PHYSIOLOGY OF BACTERIUM LACHRYMANS 

 MORPHOLOGICAL CHARACTERS 



As it occurs in the plant and also on media the organism causing the 

 disease is a short rod with rounded ends, single or in pairs (PI. XLVIII, 

 fig. 2 and 3), o.8ju wide by i to 2ix long. On culture media it occurs 

 singly or in pairs with a very decided constriction, and occasionally (in 

 salted bouillons) in chains of as many as 12 or more individuals (PL 

 XLVIII, fig. i). No spores have been seen. Capsules are formed on 

 agar (PI. XLVIII, fig. 2), and in milk (Ribbert's stain). It is motile 

 by means of i to 5 polar flagella (PI. XLVIII, fig. 3). It is Gram- 

 negative and is not acid-fast. 



EFFECT OF DESICCATION 



When drops from 24-hour peptone bouillon were placed on sterile 

 covers in sterile Petri dishes and kept in the dark at room temperature, 

 the organism was not killed by 21 days' drying, but it gave no growth 

 when covers were dropped into suitable bouillon after 6 weeks' drying. 



TEMPERATURE RELATIONS 



The best growth was obtained at 25° to 27° C. There was no growth 

 at 36°, though bouillon was weakly clouded at 35° C. Slow growth 

 occurred at 1° in bouillon cultures (two weeks' time). 



SENSITIVENESS TO SUNLIGHT 



A*ar plates, thin-sown, from an 8-day bouillon culture were exposed, 

 bottom up on ice, to sunlight in June for 5, 10, and 15 minutes, one-half 

 of each plate being protected from the light by several thicknesses of 

 black paper. After five days' incubation mmierous colonies appeared, 

 and no difference was observed between the insolated and covered side 

 on any of the six plates (but the colonies were not counted). Another 

 test was made in September, 191 5, with the following results: 



The fluid used for inoculation consisted of one 3-mm. loop from a 

 24-hour bouillon culture into 10 c. c. of bouillon. Five plates were 

 inoculated, each with one 2 -mm. loop from this suspension. Five other 

 plates were inoculated, each with one needle from this suspension. One 

 plate from each lot was then half covered and exposed bottom up on ice 

 for 5, 15, 30, 45, and 60 minutes, respectively. Result: All were killed 

 by 45 and 60 minutes' exposure; three-fourths were killed by 30 minutes' 

 exposure; one-third were killed by 15 minutes' exposure; and one-fourth 

 were killed by 5 minutes' exposure. 



When these results were obtained with the 24-hour bouillon, the experi- 

 ment with the 8-day bouillon was repeated. Four agar plates were poured, 

 one-half of each being exposed bottom up on ice, two for 15 minutes and 

 two for 30 minutes, the sky being clear and the sun bright (October 12). 



