H. 0. Paine 07 



B. phijiopJithorus was most fre(|iiently employed and Johnson (1H) states 

 that he isolated this organism from diseased potatoes in Ireland in 1906. 

 His evidence however has not been published, and the differences between 

 B. phijfophdiorus and another strain B. melanogenes isolated in the West 

 of Ireland by Pethy bridge and Murphy (34) are so slight that it is con- 

 ceivable that they were overlooked by Prof. Johnson. The B. melano- 

 genes strain was isolated by the author (32) from potatoes grown in 

 Lancashire and it is possible that it is the only one present in the 

 British Isles^. 



B. 'phytophthorus was not included in the strains examined and found 

 to be identical by Morse but he had before him a culture of B. nielanogenes 

 and this under similar cultural treatment gave identical reactions with 

 B. atrosepticus. 



B. atrosepticus is a medium-sized bacillus with rounded ends motile 

 by 3-6 peritrichous flagella and does not stain by Gram's method. 



Distribution. This disease has been reported from all parts of the 

 British Isles but the causal organism has been isolated only in the three 

 instances mentioned above. It is a disease which seems to be definitely 

 on the increase and unless some efficient means of control can be found 

 may cause a great deal of trouble in the near future. 



Host plants. Carruthers (9) isolated an organism from beans {Vicia 

 Fa6a) which he beheved to be identical with B. atrosepticus and the author 

 has found that this organism is strongly parasitic towards Vicia Faba, and 

 Appel(i) has shown that besides beans, carrots, turnips, cucumbers, 

 tomatoes, sugar beet and mangolds are also liable to attack. 



Brown Rot of Potato and Tomato. 



A disease which has been very fully described by E. F. Smith (42) in 

 which the vessels of potatoes and tomatoes become blocked with bacteria, 



1 Johnson has stated (20) that he has isolated three other organisms from diseased 

 potato plants in Ireland, namely, B. caulivorus, R. solanincoln and Kramer's bacillus to 

 which Migula gave the name B. solcmiperdn, no evidence in support of the identification is 

 however produced. B. caulivorus has been considered by Laurent (24) to be identical with 

 B. fliiorescens Uquefaciens the pathogenicity of which still remains rather doubtful and is 

 being investigated at the present time in this laboratory; it was found that from a prick 

 infection with B. atrosepticus of a bean stem without special precautions to sterilise the 

 epidermis the resulting rot gave a pure culture of a fluorescent bacillus and it is possible 

 that whenever B. fluorescens has been isolated from diseased plants its existence is a 

 saprophytic one following initial attack by some other organism. The pathogenicity of 

 B. sohinincohi has been called in question by Smith (42) and there is some doubt expressed 

 by Ajjpel (2) as to whether the experiments of Kramer (23) are sufficient to establish the 

 pathogenicity of bis bacillus also. 



