DISEASES OF PLANTS. 859 



plants bear sickly looking- leaves of a yellowish-green color. The nodes 

 where the tubercles are formed are 2 or .'5 times their normal size. The 

 organism causing this disease is 1 to 2t in length, cylindrical, with 

 rounded ends. It grows more rapidly upon gelatin than on agar. 

 Comes is said to have identified the organism as Bacterium gummis, 

 but the author considers it identical with Bacillus ampelopsorce. The 

 disease is thought to be propagated quite extensively through the 

 roots, which were observed to bear numerous excrescences. 



The necrosis of the grapevine is said to be the same disease as that 

 called mal nerOj or bacterial gummosis. It is characterized by the 

 sickly appearance of the shoots of the present year's growth, which are 

 also much shorter than healthy ones. They are of a yellowish color, 

 with characteristic gangrenous black ulcers at the point of connection 

 of the shoot with the vine proper. These ulcers are sometimes of a 

 circular form, but more often extend in long narrow strips half the 

 length of the internode. Accompanying these there is a depression or 

 corrosion of the tissues, the woody fiber and even the pith being 

 affected. The leaves become yellow and wither and the bunches of 

 grapes are arrested in their development and completely dried up. 

 The bacterial origin of this disease is said to be well established, and 

 according to the author is Bacillus vitivorus. Cultivated on gelatin the 

 bacillus is 1 to 2 // in length. It possesses considerable vitality, since 

 cultures remained alive all winter in the laboratory where the tempera- 

 tures varied from 4 to 25° C. Six successful inoculation experiments 

 with the organism are reported. Close pruning and sulphuring the 

 bunches of graphs with equal parts of sulphur and lime, after which 

 the vines are sprayed several times with Bordeaux mixture, is said to 

 be efficient in arresting the disease. 



Necrosis of mulberry trees has received considerable attention on 

 account of its destructive nature. The author has isolated 2 bacteria, 

 one of which is probably Bacillus cubonianus and the other a new 

 species to which the name B. mori-cameus is given. Both organisms 

 have been cultivated on artificial media and their characteristics are 

 described. 



The peach tuberculosis is said to be caused by Glostridivm persicce- 

 tuberculosis, a new species of bacteria, the characteristics of which are 

 described at some length. The disease, which has occurred quite 

 abundantly in the vicinity of Pavia, is characterized by the presence 

 of tubercles upon the branches of 1 or 2 years' growth, but are rarely 

 found on older ones. They are of globular or flattened globular form, 

 1 or 2 cm. in diameter. At first they appear as slight protuberances, 

 corresponding ordinarily to the first appearance of a bud, and they 

 cause the epidermis to be raised, constituting a sort of hyperplasm of the 

 cortical parenchyma. The presence of these tubercles usually kills the 

 branch, although it may survive until the second year. The tissues 

 affected are not confined solely to the bark, but extend to the woody 

 17950— No. 9 5 



