Apr. 15. 1915 Pseudomonas Citri no 



these cankers by plating out on beef agar and was found to be identical 

 with the original organism. Inoculations on grapefruit plants with the 

 organism obtained from this reisolation produced characteristic cankers. 



The open surface of the canker and the spongy character of its structure 

 afford an excellent lodging place for spores of all sorts, and it is not 

 surprising to find fungi, some of which may perhaps play a minor part in 

 the later stages of the disease. A number of fungi have been isolated 

 from old Citrus cankers, and a study of their relation to the canker 

 problem shows that the fungous flora of the Citrus canker perhaps may 

 be an interesting problem in itself. 



The organism appears to be a new species and is briefly described as 

 follows : 



Pseudomonas citri, n. sp. 



This organism is a short, motile rod with rounded ends and a polar 

 flagellum. It occurs singly or in pairs and varies in shape from a short, 

 elHpsoidal form to the typical rod. Its dimensions show corresponding 

 differences, but rod forms usually are 1.5 to 2 by 0.5 to 0.75//. 



When plated out on beef agar at room temperature, the organism 

 appears at the end of 36 to 48 hours, the colonies showing up as fine, 

 glistening points just visible to the naked eye. The surface colonies 

 increase quite rapidly in size and in three or four days show very dis- 

 tinctly. They are circular in outHne, with entire margins and a slightly 

 raised, smooth surface. By reflected light the colonies show a dull 

 yellowish color, while a bluish translucent color is observed by trans- 

 mitted light. The internal structure is finely granular and the motility 

 of the organism can sometimes be noted in the outer border of the colony 

 by examining the culture under the low power of the microscope. 



In needle-stroke cultures on beef agar a moderate filiform growth is 

 produced which does not penetrate the agar. The streak widens slowly 

 and spreads more at the base of the slant surface. The bacterial mass is 

 slightly raised, smooth, shining, and dull yellow in color. 



A very characteristic growth is obtained on potato cylinders. In 

 young cultures the organism follows the line of the streak and produces a 

 somewhat raised, shining growth which has a bright-yellow color. A 

 narrow, white zone is noted on the uninfected surface of the potato, fol- 

 lowing the margin of the bacterial mass. This feature does not persist 

 very long, as the organism grows vigorously on this medium and soon 

 the entire surface of the cylinder is covered with a thick, yellow, shining, 

 viscid mass. 



Beef bouillon shows a visible growth in 24 hours. In older cultures a 

 yellow ring is formed at the surface. 



Litmus milk shows a deeper blue color, the casein is precipitated, and 

 the clear supernatant liquid appears a deep reddish color when viewed by 

 transmitted light. 



