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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



characters." Each of these brings in a component which is visible by 

 itself on the magenta or pink ground, and adds independently to the 

 intensity of the deeper forms. Two of them, one wholly, the other 

 almost wholly, self-colours, tinge the whole flower, the third connected 

 with the occurrence of clusters of golden yellow plastids chiefly affects 

 the standard producing marked bicoloured forms. Thus deep or pale 

 magenta is dominant to scarlet or salmon sap colour, and magenta sap 

 may be pure or tinged with yellow, and salmon sap pale or deep. 

 Whatever the sap colour, absence of yellow plastids is dominant to their 

 occurrence. " There are thus between deep or pale magenta and deep 

 scarlet or salmon a number of forms intermediate in yellowness," and 

 they may be arranged in two categories, each self-coloured form having 

 a corresponding bicoloured one to which it is dominant. The self- 

 coloured form has no plastids, the bicoloured one has numerous plastids 

 in its standard. 



In the absence of yellow plastids the flower does not " bum." 



It appears also that two factors are necessary to produce the intensi- 

 fication by which pink becomes red. The paper must be consulted for 

 full details concerning the behaviour of the families obtained. — F. J. C. 



Tobacco Insects, Methods of Controlling-. By A. 0. Morgan. 



(U.S.A. Dept. Agr. Bur. Entom., Circ. 123; June 10, 1910, 11 figs. 

 2 tables). — In the investigations carried on by the Bureau all insects 

 found affecting tobacco have been studied, but particular attention has 

 been given to the tobacco flea-beetle [Epitrix paroula Fab.) and to the 

 tobacco horn-worms [Phlegethontius sexta Joh., and P. quinquema- 

 culata Haw.). In this particular circular only these insects are con- 

 sidered, a description being given to them, their ways, and the best 

 means of controlling them. — V. G. J. 



Tree Diseases, Experiments with. By E. Miinch {Nat. Zeit. 

 Land. Forst. vol. viii. p. 389 and p. 425, 1910). — In a lengthy research 

 the author examines the course of infection of a number of Polyporeae, 

 the fungi so destructive to growing timber. Trees were infected by 

 means of pure cultures of the various fungi, and the results investi- 

 gated. Besides species already well-known as destructive, the action 

 of other doubtful species was also examined, so that the investigation 

 throws considerable light on the earlier stages of tree-rot. — W. G. S. 



J1 OCT. 1911 



