390 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



roots tocks being largely used by the nurserymen there, owing to a very uncer- 

 tain percentage of hybrid trees developing in the nursery from nuts gathered 

 from trees subject to the influence of interpollinations, and, in addition, it 

 require? = Ur:hVL kur.vleige id se03.ra.te these hybni roots from those o: the 

 hl£:h soecies.— C. H. H. 



Water Requirements of Plants. Relative. By L. J. Briggs and H. L. 

 Sha-tz 7::ir. Agr. Res. iii. 0:t. 10:4. :r. 1-04 ; plates .—A large number of 

 exoeriments are recorded designed to ascertain the relative amounts of water 

 required by different plants in order to maintain their growth and reach their 

 full development. Tne amount of water required by different varieties of the 

 same species varies enormously, and it is hoped that in this direction success 

 may be obtained in raising strains of plants of economic importance for cultiva- 

 tion in dry districts. — F. J. C. 



Whitewash. Queer.*:. v:-.: Ap\ Jour. Feb. 1915, p. 60.' — A cheap lime- 

 wash which will stand the rain and weather without coming off, and that will do 

 for galvanized iron, is made as follows : — Place enough tallow in a large bucket, 

 then lay about the same quantity of good lime (dry) on top of the tallow — i.e., 

 equal proportions of each ; then pour enough water on to slake the lime. \Yhen 

 the heat from the lime has melted the tallow, and all is well dissolved, stir it 

 thoroughlv until all is well mixed ; then apply (warm if possible) with a large 

 brush. This will do for any surface. The surface must be quite dry before 

 applving the mixture. If required to dry verv white, add a small quantitv of 

 blue".— C. H. H. 



Wood Preservation, The Toxicity to Fungi of various Gils and Salts, particularly 



those Used in. By C. J. Humphrey and R. M. Fleming (U.S.A. Dep. Agr., Bur. 

 PL Ind., Bull. 227, Aug. 1915, pp. 1-3S ; 4 plates). — The principal preservatives 

 for wood are coal-tar creosote and zinc chloride, either alone or in combination. 

 It is only within the past decade that laboratory tests to determine the 

 relative toxicity of substances adapted particularly for wood preservation have 

 been undertaken. The problem has been attacked in two ways : — 



(1) By mixing the preservative under consideration with various types of 

 culture solutions solidified by the addition of agar or gelatine, and inoculating 

 with the organisms desired, and (2) by injecting the preservative into wood and 

 then exposing the blocks thus treated to the action of wood -destroying fungi. 

 These tests were first suggested by Malenkovie in 1904. 



The authors carried out a number of experiments, using the Petri dish method 

 and agar media, and also injecting the preservative in wood and exposing to 

 the destructive fungi. The cultures were grown satisfactorily on beef malt agar, 

 slightly acid. The fungi used were Fomes annosus Fr. and Forms pirn cola 

 (Sw.) Fr., while the preservatives tested were coal-tar creosote, sodium fluoride, 

 cresol calcium, zinc chloride, water-gas tar, wood creosote, hardwood tar, 

 avenarius carbolineum, copperized oil, &c. 



The conclusions drawn were : — 



The action of toxic agents appears to be specific, being highly poisonous to 

 certain organisms, but only moderately so to others. Very dilute concentrations 

 ordinarily produce a stimulative effect. The common moulds are more resistant 

 to poisons than the true wood-destroying fungi. 



The chemical and physical composition of the media supporting the growth 

 of the fungi determines, to a large extent, their development. 



Toxic elements or radicals are often difficult to determine. In heavy metallic 

 salts it is the metal ion ; in strong inorganic acids the hvdrogen ion is said to be 

 the important element ; in certain phenols the introduction of halogen, alkyl, 

 or nitro groups is said to increase toxicity. 



The results of the tests show that Fomes anmdosus Fr. is more resistant to 

 the preservatives than Fomes pinicoia (Sw.) Fr. There is a short bibliography 

 appended. — A. B. 



Xenia, Heredity of, in Certain Races of Beans. By Jean Daniel {Re : . Hori. 

 June 1, 191 4, pp. 253-27 ; col. pi. and 7 ill.). — A very interesting account of 

 results of experiments on Mendelian lines, the coloured plate showing effect of 

 crossing on both seed and flowers of the two species concerned. — C. T. D. 



Xerophiiy of Ericads in Winter. By Frank Caleb Gates {Bot. Gaz. Ivii. June 

 1914. pp. 445~4 S 9 ; 12 figs.). — The author's experiments with Chamaedaphne, 

 Vaccinium, Andromeda, &c, show that transpiration proceeded on winter days 

 even at temperatures of — 29 0 , but was often imperceptible at night. 



