BROWN ROT OF SOLANACEAE. 211 



them but which were free from Bad. solanacearum. The plants were watered with ordinary water; 

 they grew well, blossomed, and bore for the most part small fruits. The disease did not develop. 

 In another experiment, identical with the preceding, except that the plant was watered with 

 water containing a pure culture of Bact. solanacearum, the disease developed after 27 days and the 

 adventive root-formation was already under way. The plant died just one month after the beginning 

 of the experiment, and both a macroscopic and a microscopic examination demonstrated the typical 

 phenomena of the bacterial disease. 



As already stated, Dr. Hunger believes the disease is induced mostly through the inter- 

 vention of Heterodera. He thinks the bacteria are carried up the vessels by the water- 

 movement, but he does not bring sufficient proof in support of this latter statement. He states 

 that infection is not limited to the vessels, but may occur throughout the entire vascular 

 bundle, and also in the phloem and the parenchyma. The sieve-tubes may be plugged by 

 the bacteria. He thinks the adventive roots are due to the action of the bacteria on the 

 phloem. By placing wet moss around a stem showing these adventive roots, he induced them 

 to develop further and on removing this part of the plant and setting it out in the earth he 

 obtained a new plant, which grew well for some time, but afterwards developed the disease. 



He obtained his pure cultures used for infection from Petri-dish poured plates on agar. 

 This agar had the following composition: water 1 liter; agar-agar 20 grams; glucose 10 

 grams; peptone 10 grams; magnesium sulphate 0.5 gram; potassium phosphate, 0.5 gram. 



Dr. Hunger states in a number of places that the color of the surface colonies on this 

 medium was "leverkleurige," that is, liver-colored. They were small and round, and spread 

 slowly in a concentric manner. In the writer's experiments colonies of Bact. solanacearum 

 were not brown (liver color) until after a week or two. 



He states that the least amount of acid in the agar exerts an injurious influence on the 

 bacteria, but that the addition of alkali favors their growth, for example, the addition of 

 sodium phosphate. He found the organism sensitive to sunlight, development being abso- 

 lutely hindered by it, and a long exposure destroying it. 



He states that Bact. solanacearum is early contaminated in the plant by the presence of 

 other organisms. These impurities consist of saprophytic bacteria, and especially a yeast. 

 In size and shape this yeast, which he seems to have found quite common, corresponds 

 exactly to van Breda de Haan's statement respecting his coccus from tobacco plants, viz, 

 round and 8/x in diameter. We may assume either that this was what van Breda de Haan 

 saw in his diseased tobacco, or that his measurement is erroneous. If for the 0.008 mm. of 

 the text we should read 0.0008 mm., then it is easy to understand how the short rod might 

 have been taken for a coccus, especially with objectives of only medium magnification. On 

 plate-cultures Hunger found he could distinguish colonies of this yeast readily from Bact. 

 solanacearum by the fact that the latter appeared bluish-green by transmitted light. 



There is some discussion of methods of prevention, but no certain ones are pointed out 

 other than avoidance of planting on diseased land. 



It is suggested that possibly some resistant species of this family may be found upon 

 which the tomato could be grafted. 



THE MALAY STATES DISEASE. 



In 1 910, Keith Bancroft, Assistant Mycologist, reported on a bacterial disease of potato 

 and tomato occurring in the federated Malay States as follows : 



Specimens of potato plants have been recently received from Taiping (Perak) exhibiting the well- 

 known " bacteriosis " caused by Bacillus solanacearum E. Smith. The same disease has been known 

 for two or three years to occur in Kuala Lumpur on tomato plants cultivated in vegetable gardens. 

 These two crops are but little cultivated in the Malay States, so that the disease has little more 

 than a passing interest. It is, however, interesting to record its occurrence in this country, and a 

 brief note will be given of the symptoms of the disease and of some methods of treatment which are 

 likely to prove effective. 



