76 Journal of Agricultural Research voi. vi, no. 2 



from young cankerous tissues it is usually a short rod with rounded ends 

 which measures from 1.5 to 2.5 by 0.5 to 0.75/i. In old cultures the ele- 

 ments may be ellipsoidal. No endospores have been demonstrated; nor 

 have involution forms been observed. 



The organism stains readily with solutions of carbol fuchsin, analine 

 gentian violet, and methylene blue. Only negative results have been 

 secured with Gram's stain. When the organism has been grown on 

 potato cylinders and is stained with anilin gentian violet, it has an 

 apparent capsular portion (fig. 3). This capsular portion gives rise, no 

 doubt, to the viscidity which characterizes its growth on steamed potatoes. 

 The slime on old potato cultures can be drawn out an inch or two and 

 does not dissolve readily in liquid cultures. 



Young cultures of this organism on steamed potato cylinders have a 

 very characteristic appearance. The growth is bright yellow, smooth, 

 moist, glistening, and raised, with a narrow white zone along the margin 

 of the bacterial growth. This white margin does not persist, since by 



its rapid growth the organism covers the en- 

 tire surface of the medium. It acts very 

 strongly on potato starch, as indicated by the 

 entire absence of an iodin reaction on steamed 

 potato cylinders 6 to 8 weeks old. The mid- 

 dle lamellae in such old cultures have been 

 dissolved, and the empty cells can readily be 

 separated from one another. 



The organism has been grown on nutrient 

 agar made by adding a water extract of corn 

 Pig. 3— Pseudomo7ias citri: a. stsiined nieal, bean m^eal, green beans, cowpeas, pota- 



with carbol fuchsia; 6, stained with , . . . „ i ^ i 



wSiams's flagellar stam (adapted toes, nce, oraugc jmcc, or orangc leaves and 



from Hasse); c, stained with aniUn stemS, but the grOWth On nOUC of thcSC media 



gentian violet. .^ characteristic No attempt was made to 



titrate any of these media to determine their acidity or alkalinity. 



Colonies appear on the second day in poured plates of green-bean agar 

 kept at room temperature. Within four or five days the surface colonies 

 in poured plates will have become 2 or 3 mm. in diameter. The margin 

 of the colonies is entire, and they are opaque yellow in color. They are 

 appreciably raised and have a smooth, wet-shining surface. The char- 

 acter of the margin and of the surface is shown in Plate XI, figure 4. 

 It will be noted that the reflection of the two windows in the room in 

 which the exposure was made is shown in each of the colonies. 



A filiform growth, following the Hne of the stroke and widening at the 

 base of the slant, is formed in stroke cultures on green-bean agar. The 

 growth does not penetrate the agar and does not give rise to the produc- 

 tion of any stain or odor. In stab cultures on this medium a filiform 

 but otherwise nontypical growth is produced, which when viewed from 



