414 



White (G. P.). European Foulbrood. — U.S. Dept. Agric, Washington, 

 D.C., Bull. 810, 26th February 1920, 39 pp., 8 plates, 6 figs. 

 [Received 27tli July 1920.] 



European foulbrood, which is an infectious disease of the brood of 

 bees caused by Bacillus pluton, is characterised by the death of brood 

 during its uncapped stage and by the absence of any marked odour. 

 The disorder has a wide distribution, while the losses sustained by the 

 infected apiary vary from a slight weakening of the colonies in some 

 instances to the destruction of all of them in others. 



This paper deals with some of the results that have been obtained 

 from a study of the disease from a laboratory point of view. Among 

 the problems considered are the resistance of B. pluton to heat, drying, 

 sunlight, fermentation, and disinfectants ; the effect of the disease on 

 the colony and on the apiary; and the aetiology, transmission, diag- 

 nosis, and prognosis of the disease. Work directly on the treatment of 

 the disease has not been attempted ; but any treatment that is devised, 

 if it is to be efiicient and economical, must be based upon the results 

 obtained from the solution of such problems as have been mentioned. 



Brandes (E. W.). The Mosaic Disease of Sugar Cane and other 

 Grasses. — U.S. Dept. Agric, Washington, D. C, Bull. 829, 

 29th October 1919, 26 pp., 5 figs., 1 plate. [Received 27th July 

 1920.] 



Field observations of plants sufferirig from mosaic disease indicate 

 that acceleration in the spread of the disease is accompanied with or 

 preceded by severe msect mfestation. The cane leaf-hopper {Tettigonia 

 sp.) in particular has been noticed to accompany the rapid spread of the 

 disease. The evidence in favour of insect transmission is borne out 

 by the fact that ten healthy plants in insect-proof cages in a greenhouse 

 did not contract the disease, while five plants kept outside the cages, 

 but otherwise under identical conditions, all became infected. Aphids 

 were abundant on the diseased cane in the greenhouse and a few 

 leaf-hoppers were present. A great deal of experimental work remains 

 to be done, however, before the theory of transmission by any particular 

 insect can be established. 



Shaw (H. B.). Control of the Sugar-Beet Nematode. — U.S. Dept. 

 Agric, Washington, D.C., Farmers' Bull. 772, December 1916, 

 19 pp., 6 figs. [Received 27th July 1920.] 



The sugar-beet Nematode, Heterodera schachtii, Schmidt, is found in 

 practically every European country where beets are grown. It has 

 been introduced into the United States and has become well established 

 in the older beet districts in the West, causing the same amount o f 

 damage as in Europe. This species is closely related to the root-knot 

 Nematode, H. radicicola, the points in which it difters being here des- 

 cribed. As soon as the larvae emerge they search for food, entering 

 the tissues of the rootlet and feeding on the plant juices. They moult 

 twice before transforming into the adult, after which the males at once 

 escape from the rootlet in search of the females. The latter protrude 

 from the rootlet and, when fully mature, drop to the ground and die, 

 after which the eggs hatch. Each female is capable of producing from 



