8. a. Jones 295 



were eflected from the agar-streaks into small excavations made at the 

 centre of the blocks. After an incubation period of 15 to 24 hours at 

 20° C. most of the blocks showed a whitish-grey transparency around 

 the inoculated part. In the more juicy blocks, the afiiected area, in 

 24 hours, would be about the size of a sixpence. After further incubation 

 for 24 hours they had become completely diseased; during the next 

 two or three days they assumed a yellowish hue and after a week a 

 brown colour. The organisms causing the rot in the blocks had been 

 derived from the agar-streaks which had been taken from round, whitish- 

 grey hquefying colonies. Repeated cultures from field material showed 

 that the colonies effective on the turnip blocks were of this type. Poured 

 plates taken from successfidly inoculated blocks showed the colonies in 

 crowded growth to be small, those situated below the surface of the 

 gelatine being smaller. On a thinly sown jjlate the colonies were large, 

 circular, with much hquefaction in the centre. Magnified under the 

 low power of the microscope they showed a finely, closely fibrillated 

 margin; within the margin was a narrow finely-granular zone, then a 

 narrower denser granular band forming a very faint concentric circle 

 within which was a wide zone gradually diminishing in a granular 

 density towards the centre. The saucer-like depression contained massed 

 bacterial debris floating in a thinly granular hquid. Buried colonies 

 were small, round, fibrillated at the margin and homogeneously granular. 



The Organism .4nd its Flagell.\tion. 



After repeated cultures had been made in nutrient gelatine from the 

 diseased blocks there remained no doubt that a pure culture had been 

 obtained. Cover-sUp preparations of the organisms stained with carbol- 

 fuchsin showed them to be rod-like in form and of varying length. Single 

 specimens were short with rounded ends and pairs were frequently seen. 

 Hanging-drop cultures in bouillon from several young agar-slants showed 

 the organisms to be actively motile. After repeated attempts to stain 

 the flagella, it was found effective to transfer the organism from agar- 

 streaks of not more than 12 hours' growth into a number of small petri- 

 capsules half-filled with sterile, filtered water kept at the same tem- 

 perature as that in which the agar-cultures were incubated. The cover- 

 sHps were placed in series of six in a large petri-dish bearing the corre- 

 sponding number of the culture. A sterile platinum loop was then dipped 

 into the small capsule and the drop quickly deposited on the cover-shp, 

 six preparations being taken from the same capsule. These were air-dried 



