248 



I MICRO-ORGANISMS IN THEIR RELATION Ta 

 TOBACCO PLANTING AND TOBACCO 

 MANUFACTURE. 



A Eeview by Dr. Behrens. 



Abstracted and translated from Centralblatt fur BaMeriologie and" 

 ParasitenkUnde by Percival H. Greg. 



Among diseases supposed to be caused by the activity of Micro-or- 

 ganisms, the -writer mentions the " mosaic disease/' which makes its ap- 

 pearance in certain districts of the Netherlands, and also in Germany. 

 Tobacco leaves attacked in this manner take cn a sort of mosaic-work 

 pattern, caused by some parts of the leaves taking on a darker, 

 others a lighter shade, Those parts that take on a lighter shade are 

 thinner and finally die ; the leaves then curl up, and for that season 

 are useless for manufacturing purposes. Adolph Mayer concludes that 

 the disease is of an infectious nature and due to the presence of an or- 

 ganised disease- producing ferment, for the reason that if the juice of 

 such infected leaves is placed on healthy leaves, especially young ones, 

 they were attacked in the same manner, while if the same juice had 

 been previously kept at a temperature of 80° C. (176° F.) for several 

 hours, treated with absolute alcohol, or filtered through several layers of 

 filter paper**the juice lost its power to produce the disease. But the 

 bacteria which were isolated out of the juice of such leaves were power- 

 less on infection experiments being performed to produce a similar re- 

 sult. In a later communication it is related how a planter was success- 

 ful in overcoming the attack by simply renewing the earth in his seed 

 beds. While 25 per cent, of the plants from the old beds were attacked, 

 among those from the new beds scarcely one diseased one could be 

 found. More recently, Breda de Haan, in two articles, has been treat- 

 ing of the nature of the Bibitziekte, a disease by which the young seed- 

 lings or cuttings in Deli are attacked. He shews that it is caused by a 

 Phytophthora which be provisionally names Ph. Xicotianas (new spe- 

 cies.) He also discovered how to battle with the disease and hold it in 

 check to a considerable extent. This consists partly in a modification 

 of the generally followed rules in raising the seedlings, which are to be 

 kept drier and more exposed to the light than was previously the case 

 partly in the employment of the copper- containing liquids which have 

 been used with such success in the case of the Peronosporea?, especially 

 the copper lime mixture. 



Other diseases of Tobacco in the various stages of its preparation are 

 spoken of as geneially considered by various investigators to be due to 

 micro-organisms, but nothing very definite appears to be known, though 

 in the case of a disease of Tobacco investigated by Sturgiss and called 

 Pole Burn, supposed to be identical with the German " Eoof Burn/' 

 the author appears to have reached some definite result. Leaves 

 so attacked are covered with dark brown to black patches, looking like 

 so many burnt spots ; in presence of sufficient moisture these patched 

 grow larger and finally cover the whole leaf, which then becomes soft 

 and wet, and is easily torn on being handled. It is, in fact, a decompo- 



