418 A Tomato Canker 



On gelatine the average length is slightly greater, being 2-3 fi, and 

 the breadth is -6 to -65 /A. Limits observed were 1-4 x '6-'7/x. The rods 

 were mostly single but occasionally in pairs or short chains. 



In 24 hours old potato cultures the rods are also rather long as com- 

 pared with those on agar cultures; the majority are 1-5-2-5 x -6/x. There 

 are numerous pairs and short chains, and occasionally long threads up 

 to 40 jx long which are only partially or imperfectly segmented. After 

 six days the size and grouping remain the same, with the exception of 

 the long threads which are no longer seen. 



Motility. The organism is actively motile in very young cultures. 

 In hanging drop cultures it moves with a forward screwlike action, 

 its progress being frequently interrupted by rotations on its short axis 



Fig. 4. Rods from streak incubated for 18 hours at 20° C. 

 Stained by Loffler's method. 



and other tumbling movements. The rods gradually made their way to 

 the edge of the drop and came to rest. The organism is not motile as it 

 diffuses from the tissues of the host. Rods from a young agar culture 

 examined with the dark ground illumination showed no highly refractive 

 granules, and the rods are apparently motile by means of a polar flagelium 

 on the forward end which whirls like the propellor of an aeroplane. 



This observation was confirmed by the examination of stained pre- 

 parations. Good preparations were not very easy to obtain as the 

 organism sheds its flagella very readily ; fairly good results were obtained 

 with a modification of Loffler's method and by van Ermengen's method. 

 There is a single polar flagelium with a length of about 5-10/z (Fig. 4). 



Spores were not observed. 



