Apr. lo, 1916 Citrus Canker 



77 



above appears like the surface colonies in poured plates. Growth in 

 stab cultures on various media is always or nearly always best at the 

 surface of the media. 



On nutrient-gelatin plates the colonies are circular in outline, slightly 

 raised, entire margined, and yellowish. In gelatin stabs a filiform growth 

 appears along the line of puncture, with the greatest growth at the 

 surface of the medium, and with a rather slow liquefaction. 



The organism is regarded as a facultative anaerobe. No gas is formed 

 in fermentation tubes containing a 2 per cent solution of Witte's peptone. 

 With this as a basal solution, five solutions were made by adding i per 

 cent of one of the following carbon compounds: Saccharose, dextrose, 

 lactose, maltose, and glycerin. All inoculated tubes developed a slight 

 cloudiness, which extended into the closed end of the tube by the second 

 day. More vigorous growth occurs in the open end of the tube, however, 

 and after four or five days the cloudiness is very marked. Yellowish 

 flocculent particles appear later in the open end, and a yellowish ring 

 is formed at the surface. No gas formed in any of the solid media in 

 which the above-mentioned carbon compounds were added to the nutrient 

 agar. 



In stab cultures on litmus-dextrose, litmus-lactose, litmus-saccharose, 

 and litmus-glycerin agar no gas formation was apparent in lo-day old 

 cultures. It is not known whether acidification will occur in old cultures 

 on these media. 



In sterile tubes of litmus milk there is a rather slow reduction of the 

 litmus. After five days there is a slight increase in the blue color. The 

 reddish whey is gradually formed on the surface, and the casein is 

 precipitated. 



There is no reduction of nitrates in Witte's peptone solution containing 

 a trace of potassium nitrate. Phenoldisulphonic acid was used as a 

 reagent 10 days after the date of inoculation, at which time both the 

 check and the solution in which the organism was growing were colori- 

 metrically alike. 



Only negative tests for indol were secured in peptonized beef-bouillon 

 cultures. A very conspicuous clouding occurs in this medium within 24 

 hours after inoculation. As these cultures get older they become some- 

 what flocculent, and a yellowish ring is formed at the surface of the 

 media. 



The thermal death point, as found in preliminary tests, was between 

 58° and 70° C. In order to determine more nearly the point, tests were 

 made by exposing the organism taken from potato cylinder cultures, and 

 transferred to tubes of bouillon. The tubes were then placed in a water 

 bath for 10 minutes at some given temperature between these Hmits. 

 The temperature of the bath was kept constant during the period of 

 exposure. The tubes were subjected to room temperature for several 



