404 BACTERIUM CAMPESTKE IN SOUTH AFRICA. 



A small plot in the laboratory grounds was planted with 

 about 36 cabbages in six rows. On November 24th these plants 

 were all apparently quite healthy, and six cabbages in the row- 

 nearest to the fence were inoculated with a pure culture of the 

 same origin as that used in the previous experiments, two by 

 needle pricks in the midrib of a leaf, and four by placing traces 

 of the culture on the leaf margins. The weather was warm and 

 moist, the rains having set in during November, and signs of 

 infection were quite evident on December loth on the inoculated 

 plants. All the j^Iants on the remainder of the plot were per- 

 fectly clean, and remained so up to the middle of December, 

 when the writer left F'retoria for a month. During that time 

 the same weather conditions prevailed, over 20 inches of rain 

 falling during December and January. On the 20th January 

 the six cabbages inoculated were very badly diseased, consisting 

 of a long stalk with cons])icuous leaf scars surmounted by a 

 loose head, and surrounded by fallen and decaying leaves. One 

 of these was ohotograDhed, and is re])roduced in Plate y a. 

 The disease had spread rieht through the ])lot ; those in the row 

 most remote from the inoculated plants only showing a very 

 few water-pore infections, but those in their immediate vicinity 

 being badly affected. 



On March 19th, a similar disease was noticed in some kohl- 

 rabi plants at Groenkloof Experiment Station; a yellow organism 

 was plated out from these plants, and four young cabbage 

 plants inoculated with the cultures. These readily contracted 

 the disease, infection being ver\' evident after about two weeks. 

 The controls remained healthy. 



A similar experiment was carried out using cultures 

 obtained from diseased swedes ; this inoculation was also suc- 

 cessful. 



It has been mentioned in an earlier part of this paper that 

 the cabbages in the writer's garden which developed the disease 

 had been obtained as seedlings from a local seedsman. On visit- 

 ing the nursery where they had been grown late in November, 

 I found that the disease was present right through the seed beds, 

 and was thus being distril)uted right through the district, as 

 people with small gardens usually buy seedlings rather than 

 raise the plants from seed. An inspection of other nurseries 

 would most likely lead to similar discoveries. In the case in 

 question, the evidence pointed to the seed as the source of in- 

 fection, and the nurseryman very kindly furnished me with a 

 sam])le packet of each variety of seed which he had planted, and 

 which had been imported from England. From these seeds a 

 yellow organism was isolated ; two cabbage plants were inocu- 

 lated with the organism, and they readily contracted the disease. 

 It is evident, therefore, that at least one source of infection is 

 imported seed, it being impossible at this distance to ascertain 

 whether the seed has been obtained from a healthy crop. 



