400 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Agr., Bur. PI. Ind., Bull. 230). — The object of this investigation was 

 to determine the extent of the variation exhibited by different plants 

 with respect to the minimum point to which they can reduce the 

 moisture- content of the soil before permanent wilting occurs. The 

 conclusion reached was that the differences exhibited by crop plants 

 in their ability to reduce the moisture-content of the soil before wilting 

 occurs are so slight as to be without practical significance in the 

 selection of crops for semi-arid regions. As an example, two such 

 different plants as a Coleus and Kubauka wheat wilted simultaneously 

 when grown in the same soil mass. — D. M. G. 



Wilting" of Plants. By Lyman J. Briggs and IT. L. Shantz {Bot. 

 Gaz. pp. 20-37, Jan. 1912). — After plants have wilted by having too 

 much reduced the water- content of the soil, there is still a loss of water 

 from the soil to the air which goes on through the plant-tissues even 

 after the plant is dead. 



This paper on ' ' The Wilting Coefhcient and its Indirect Determina- 

 tion ' ' deals with the amount of water usually called non-available that 

 is absorbed by the dying or dead plant and evaporated. The plants 

 (wheat seedlings) were grown in wax-sealed pots. The authors define 

 the wilting coefficient as the percentage water-content of a soil when 

 plants first wilt to such a degree that they cannot recover without the 

 addition of water. 



This wilting coefficient was found equal to (1) the moisture equivalent 



hygroscopic coefficient 

 divided by 1.84 (1 ± 0.007); (2) ^oMir'±mi&)^ ' moisture 



holding capacity -21 divided by 2.90 (1 ± O.F2I); and (4) 0.01 sand + 

 0.12 silt + 0.57 clay divided by 1 4- 0.025.— G. F. S. E. 



Woods of the United States, Uses of Commercial. By 



Wilham L. Hall and H. Maxwell {U.S.A. Dep. Agr., Forest Service, 

 Bull. 95, June 30, 1911). — The Cedars, Cypresses, and Sequoias are the 

 three families of trees that are here treated of, and of the Cedar alone 

 no less than eight kinds are considered as sources of lumber and wood 

 supply. A detailed account is given of the trees of Sequoia in the 

 famous Oalaveros groves, many of which are supposed to be over two 

 thousand years old. — A. D. W. 



Woolly Aphis, Red-oil Spray for. By W. H. Grant {Agr. Gaz. 

 N.S.W. vol. xxii. pt. xii. pp. 107-12).-— Eed-oil emulsion, owing to 

 its penetrative properties, is more effective than kerosene emulsion for | 

 destroying woolly aphis on apple trees. The mixture contains 4 gallons 

 of red oil, 3 lb. hard soap, and 100 gallons of water. It should be j 

 w^arm when used and applied the day it is made. — S. E. W . 



