196 SCIENCE PROGRESS 



ten years later (1895) Waite fully substantiated the origin of 

 the disease by isolation of the bacterium {Bacillus auiylovonts) 

 and successful infection with pure cultures. 



Yellow Disease of H3^acinth. — Abundant proof was forth- 

 coming in support of Wakker's conclusions with regard to 

 Pseudomonas hyacinthi ; the parasitic nature of this organism 

 was fully confirmed by Smith in 1896. 



The Canker of the Olive — Bacillus olcce — which produces 

 galls or irregular tubercular swellings on the branches of these 

 trees, was investigated by Archangeli and Savastano in 1886 

 and definite proof given by the latter in 1889 and by Cavara 

 and Prillieux in 1890. 



The Corn Blight — Bacillus zca— was described by Burril in 

 1889. The plants are stunted and yellow in colour, the disease 

 first appearing on the lower leaves and brown spots on the 

 surface of the roots. 



The Soft Rot of Hyacinth — Bacillus hyacinth i-scplicus, by 

 Heinz — appeared also in 1889. The flowers either fail altogether 

 in the bud or they open in very irregular order and soon tumble 

 off. At the same time the axis of the inflorescence falls over 

 and rots and the bulb degenerates into an evil-smelling slime. 



The Potato Wet Rot — Bacillus solanipcrda — was published by 

 Kramer in 1890-91. He showed that the bacteria break down 

 first the soluble carbohydrates, then destro}^ the intercellular 

 substance and attack the cell-wall ; the starch is not attacked 

 but at a later stage the proteids also are destroyed. 



The Bacteriosis of the Vine — Bacillus uvecc — was the work of 

 Macchiati in 1894. After the flowering the young fruits and 

 peduncles turn brown, shrivel up and become a completely dry, 

 brittle mass. 



The Cucurbit Wilt — Bacillus trachciphilus. In this investi- 

 gation Smith describes a peritrichiate bacillus, more particularly 

 occupying the spiral vessels and later the tracheids. The most 

 marked symptom is the wilting of the leaves ; afterwards the 

 bacilli pass through the conducting channels to the stem and 

 eventually all the internal tissues become more or less 

 destroyed. 



The Brown Rot of Cruciferae — Pseudoniouas campestris — was 

 established by Pammel in 1895 and fully confirmed by Smith 

 in 1896. The organism is pathogenic for various Cruciferous 

 plants, which are affected through the vascular system. The 



