386 AGRICULTURAL BACTERIOLOGY. 



and in Australia. It spreads very rapidly under certain cir- 

 cumstances, sometimes a whole district being infected in the 

 course of a single season, so that the industry of the bee-maker 

 is nearly ruined. This disease is produced by a bacillus, named 

 B. alvei, that has been known for some years and has been 

 definitely proved to be the cause of the disease in question. 

 It is carried from hive to hive, as now believed, chiefly by the 

 robber bees ; that is, by bees who steal honey from other hives. 

 They can readily steal from a hive that has become weak- 

 ened by the action of the disease, and such hives, of course, 

 would be the very ones from which infection would be ac- 

 quired. It is also distributed by the custom of selling bees, 

 or sometimes by the custom of selling hives which have been 

 infected by the disease. Remedies against it are not thor- 

 oughly efficacious. One is the radical method of destroying 

 the hive, together with all its bees, as soon as the disease makes 

 its appearance. A less radical method is to separate the bees 

 from their larvae and their honey, keeping them for a day or 

 two without food and then putting them into a new clean hive, 

 destroying or thoroughly disinfecting the old one. This will 

 ordinarily result in the disappearance of the disease. Other 

 more or less successful methods of meeting the disease are by 

 the use of various chemicals. 



BACTERIAL DISEASES AMONG PLANTS. 



The bacterial diseases of plants have been far less studied 

 than those of animals. They have excited less interest and few 

 bacteriologists have hitherto turned their attention to their 

 study. The whole subject of bacterial plant diseases has been 

 much disputed. In earlier years it has been claimed impos- 

 sible for plants to have bacterial diseases. Plants are covered 

 by an impervious cuticle through which bacteria cannot nor- 

 mally pass. Moreover, the tissues of the plant are not filled 

 with nutritious fluids as are the tissues of animals, the spaces 



