682 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



mixed with Deschavifsia caespitosa, and by Mercurialis pefennis. 

 The societies of the Oak wood association are dominated by Holcus 

 mollis and Pteris aquilina, and by Holcus mollis alone. The con- 

 ditions of water contents of soil, intensity of light, &c., characterizing 

 each of these societies is analyzed. It was found that those plants 

 whose structure was most capable of modification by the varying con- 

 ditions of life were able to withstand a great range of conditions. 



R. B. 



Wood of Dying- and Dead Trees, Insect Injuries to the. By 



A. D. Hopkins {U.S.A. Dep. Agr., Bur. Entom., Circ. 127; Dec. 

 1910). — " Timber dying from insect attack and other causes, including 

 fire, disease, storms, &c., is attacked by certain wood-boring insects 

 which extend their burrows through the sound sapwood and heart- 

 wood, and thus contribute to the rapid deterioration and decay of a 

 commodity which otherwise would be available commercially during 

 periods of from one to twenty years after the death of the tree." 



Fire-killed and storm-felled pine, fir, spruce, &c., are in particular 

 attacked by the boring larvae known as " sawyers," which, after 

 feeding on the inner bark for a time, extend their large burrows into 

 the heartwood. 



Timber-beeties make pin-holes in the sapwood, which render the 

 wood defective and encourage a wood-staining fungus to which the 

 holes give entrance. 



Great damage is done to the wood of hickory, ash, oak, and chest- 

 nut by the round-headed wood-borers (Ceramhycidae), timber-worms, 

 and ambrosia beetles, the wood being frequently reduced in value 

 10 to 25 per cent. 



Injury may be prevented by (1) prompt utilization of such timber 

 after it is dead or past recovery; (2) removal of the bark from the 

 merchantable portions of the timber as soon as possible; (3) felling 

 the trees and placing the unbarked logs in water. — V. G. J. 



Wood Preservatives and Quantity of Wood treated in the 

 United States in 1910, Consumption of. By H. S. Sackett {U.S.A. 

 Dep. Agr., Forest Service, Circ. 186; Aug. 2, 1911). — This is an 

 account of how rapidly the treatment of timber by impregnating with 

 various chemicals has come about in the United States. In 1909 there 

 were no less than eighty commercial plants for treating timber in this 

 way. — A. D. W. 



Zinc ortho arsenite as an Insecticide. By E. A. Cooley 



{Jour. Econ. Entom. V, pp. 142-146; April 1912; figs.). — Ortho- arsenite 

 of zinc is a white, fluffy, finely divided powder, mixing well with water 

 after rubbing into a paste. It spreads as well as arseniate of lead, and 

 much better than Paris green. The samples tested contained less water- 

 soluble arsenic than either Paris green or arseniate of lead, and it is 

 intermediate in strength between these two. In suspension it settles 

 rather more quickly than arseniate of lead but the addition of soap 



