538 THE PATHOGENIC BACTERIA. 



that the disease was in the first instance due to bacterial action. 

 Other diseases have already been noticed amongst the '' Fungi 

 Imperfecti" (p. 464). 



Gummosis of Plants. 



There are many diseases characterized by a gummy outflow 

 from the diseased parts or from their neighbourhood. Amongst 

 plants exhibiting this are trees like the mulberry, olive, vine, 

 fig, and vegetables like potatoes, turnips, beetroot, and many 

 others. As yet, however, no investigations have been carried out 

 carefully enough to give satisfactory explanations of them. It is, 

 however, probable that they are primarily due to errors in 

 cultivation, while the bacteria which are always found associated 

 with them are of secondary importance as disease-producers. 



Bacteriosis of Bulbs. 



Hyacinth-bulbs, when stored up, are liable to several 

 diseases which bring about rot and decay. Bacteria have 

 been found in the earlier stages of the rot by several 

 observers. One of these bacterial forms described by Wakker l 

 occurs as yellow masses, particularly in the decaying fibro- 

 vascular bundles of the bulbs ; it has been named Bacillus 

 hyacintlii Wakk. Wakker succeeded in carrying out infections 

 with it, and it seems to be a definite bacterial disease. The 

 external symptoms were yellow lines on the leaves, due to yellow 

 masses of the Bacillus in the vascular bundles and intercellular 

 spaces of the parenchyma. 



Another bacterial disease of hyacinth and other bulbs was 

 investigated by Heinz. 2 The disease starts from the bulb, and 

 rapidly extends into the leaves and inflorescences, so that the 

 leaves wither and the flower-buds drop off. Shortly afterwards 

 the diseased tissues break up and become a foul-smelling slime 

 containing an almost pure culture of a bacterial form which 

 Heinz named Jiacillns hyacinthus scptieus. The Bucilltis is easily 

 cultivated on gelatine, which it does not liquefy. When applied 

 to the base of the leaves it easily infects them, penetrating in 



Wakker. So/an. Cuttralblatt, xiv., 1883; Wakker, " Onderzoek d. Ziekten 

 van Hyacinthen, etc.," Alymi. Vereeuiy. roor Bloembollenkultur, 1883, 84, 85. 

 -Heinz, Cent m/l>l(tff fur Baktrrioloyie und Parasitenkiinde, 1889, p. 535. 



