BROWN ROT OF SOLANACEAE. 209 



THE DUTCH EAST INDIAN DISEASE. 



A disease of tomatoes prevalent in Western Java and rapidly fatal was identified by 

 Dr. F. W. T. Hunger of Buitenzorg in 1901 as due to B. solanacearum Smith. The follow- 

 ing observations are from Hunger's paper (see Bibliography) : 



This disease has not been so prevalent as in the United States, but nevertheless whole 

 plantations have been destroyed by it in Java. The course of the disease is rapid. 



Hunger experimented with diseased and healthy plants, exposing them to the sun with- 

 out water and then watering them. The diseased plants recovered slowly from the wilted 

 condition, and after some days not at all. The undiseased recovered promptly on watering. 



In two instances he observed buds out of place, namely, on the leaves, and he is inclined 

 to think that these signs were due to the disease. The adventive root-formation occurs so 

 regularly that there can be no doubt as to this being a sign of the disease. The roots develop 

 regularly on the stem and they may appear also on the leaf-stalk. 



The vascular ring of the stem was stained brown and bacteria were abundant in the 

 vessels. Whenever a tomato plant showed signs of the disease above ground he always 

 found the root-system diseased. These roots were more or less browned, and when well 

 along in the disease were blackish and soft, and filled with bacteria. In early stages the 

 browning was confined to the xylem wedges of the root. 



Tissues put into alcohol of various strengths gave the result described by Smith, viz, 

 the bacteria diffused out of the vessels regularly in 75 per cent alcohol, and also to a less 

 extent in 90 per cent, but were hindered in their diffusion by absolute alcohol. Hunger 

 found that by adding i per cent nitric acid to the 75 per cent alcohol he obtained a solution 

 in which diseased tissues behaved as in absolute alcohol. He found the pith of diseased 

 plants greatly changed, i. e., from white to spotted gray, with formation of bacterial cavities. 

 The whole pith of diseased stems may disappear, the remnants being found on the inner 

 edges of the vascular ring. Groups of tetrahedral crystals, the so-called crystal-sand, are 

 stated to be much more common in diseased than in healthy plants. Hairs are absent from 

 the vicinity of those parts of stems which are sending out adventive roots [the writer has 

 not observed this in the North American disease]. These roots spring from the pericycle. 



Hunger believes that the formation of tyloses which he observed abundantly in the 

 vessels of diseased plants is induced by the presence of the bacteria. These tyloses are 

 always filled with bacteria. They soften the walls of the vessels in places and then the 

 tyloses are formed; the evidence adduced in proof of this statement is not conclusive, but 

 nevertheless Hunger is probably right (see similar observations by the writer on mulberry 

 shoots attacked by Bad. mori, vol. II, fig. 30, of this monograph). 



Hunger also notes that in Tryon's paper there is not the least description of his Bacillus 

 vascularum solani. He says: 



The bacteria found by me as cause of this tomato disease agree in every particular with Bad. 

 solanacearum Smith, so that I hold the two for identical. 



Hunger believes that he has determined by inoculation with the tomato organism the 

 occurrence of the same disease on Nicotiana tabacum and Capsicum annuum. He says that 

 he has repeatedly obtained the same signs of disease in these plants as in sick tomatoes. He 

 inoculated it into tobacco, using cultures from tomatoes, and obtained the slime-disease (see 

 Wilt Diseases of Tobacco, p. 222). His inoculation experiments were as follows: 



Tomato seeds were germinated on filter-paper and the young plants then brought into water- 

 cultures, which were infected with pure cultures of Bad. solanacearum. The young plant grew as well 

 as the check-plant, and a subsequent examination showed that there were no bacteria in its interior. 



In a similar experiment, varied only by the fact that the root-system was wounded in various 

 ways, viz, by needle-pricks and by teazing out the end of some of the young roots, the plants became 

 infected after a week and the bacteria were demonstrated in the vascular bundles. In one of the 

 plants the bacteria were found in the vessels of the leaf-stalks of two of nearly the youngest leaves. 

 Tyloses had not yet formed in these vessels. 



