100 Report or DEPARTMENT OF BACTERIOLOGY OF THE 
Having later obtained well-marked results from inoculations 
with a yellow organism which he named Bacillus campestris, 
no further work was done with the white organism which, 
in the light of later experience, appears to have been the more 
important pathogen. 
Strictly speaking, the black rot of cabbage and allied plants, 
caused by Bacillus, or as it is now called, Pseudomonas cam- 
pestris, should be included among the soft rots. While this 
disease ordinarily manifests itself by a drying and browning 
of the foliage it also often appears as a soft rot of the fleshy 
tissue.. However, as its casual organism can be easily dis- 
tinguished from the germs producing the soft rots which we 
have been studying, we have not included Ps. campestris 
among the organisms discussed in this paper. 
As has been already suggested, the prime object of our 
study was to remove the present confusion which exists as to 
the relationships of the closely allied, white organisms which 
‘ause the soft rots ef the carrot, turnip, cabbage and cauli- 
flower. 
SOURCES OF OUR CULTURES. 
Professor M. C. Potter presented the results of his study 
of a bacterial disease of turnips to the University of Durham 
Philosophical Society® in December; 1898, in which he named 
the casual organism Pseudomonas destructans, and presented 
a very similar paper at the British Association® meeting at 
Dover in September, 1899. The published abstracts of these 
papers characterized this disease as a white rot and included 
a brief description of Pseudomonas destructans. Aside from 
the pathogenicity, his description in these first papers is So 
brief that it is very doubtful if his organism could be recog- 
nized by its aid. He characterized the organism more fully in 
a paper read before the Royal Society’ in December, 1900, and 
®Potter, M. C. On a bacterial disease — white rot — of the turnip. From 
Univ. of Durham. Philo. Soe. Proce. Nov., 1899. 
*Potter, M. C. On white rot—a bacterial disease — of the turnip. — 
British Asso. for Adv. of Sci. Report for 1899: 921-922. 1900. 
~ 7Potter, M. C. On a bacterial disease of the turnip. .( Brassica Napus). 
Royal Soe. of London, Proc. 67: 442-459, 1901. Reviewed also in Ztschr. 
Pflanzenkr., 12: 170. 1902. ° 
