142 JOURNAL OF THF ROYAL HORTICULTURAL SOCIETY. 



young growth, from 75 to 150 years old. For propeller blades, for which ash 

 is very largely used, the quality desired, in addition to strength in comparison 

 with weight, is ability of the wood to hold its shape, which is best supplied by 

 old-growth ash. Propeller blades are made from laminated blocks consisting 

 of several layers of different kinds of wood glued and nailed together. An 

 excellent combination is said to be a middle layer of ash with spruce on either 

 side, then layers of mahogany on the spruce, and thin layers of ash on the out- 

 side. Engine blocks and frame ribs are also often laminated in construction 

 spruce and ash being combined to divide the stress. 



Ash lumber is an extremely valuable wood for special uses. The supply of 

 standing ash timber is becoming limited, and to maintain enough to meet the 

 demand commercial growing of the ash is necessary. 



The following are the uses for which standing ash timber containing various 

 kinds of material is most suitable and profitable : — 



1. Clear, rapid-growing second-growth timber of white, green, blue, and 

 Biltmore ash. The wood is straight- grained and strong. Trees less than 

 15 in. in diameter are most valuable for fork, hoe, shovel, spade, and scythe 

 handles, baseball mats, and singletrees and doubletrees. Trees 15 in. and 

 over in diameter are valuable for the above uses and for boat oars, wagon 

 tongues, lumber for bentwood, other parts in car and vehicle construction, 

 and sporting and athletic goods. 



2. Large, clear, old-growth ash timber of all species holds its shape well, 

 and is especially valuable for dimension lumber (largely for re-sawing) for car 

 and boat construction, interior finish, church, store, and office fixtures, vehicle 

 and automobile bodies, and agricultural and musical instruments. 



3. Crooked and knotty ash timber and small, slow-growing trees (such as 

 are found on poor, thin soils producing weak wood) and the lower grades of 

 ash lumber can best be used for butter-tub staves and heading, woodenware 

 and novelties, chair and furniture stock, hames, and other uses in which short 

 clear pieces, such as can be cut out from between knots, can be utilized. 



4. Clear black ash timber over 15 inches in diameter, the supply of which 

 is very limited, is especially valuable for butter-tub hoops, splints for baskets 

 and chair bottoms, and for interior finish. — A. D. W. 



Aster fuscescens Bur. et Franch. By J. Hutchinson (Bot. Mag. t. 8728 ; 

 September 191 7). — Native of Western China. A hardy perennial which ripens 

 seeds freely in a herbaceous border. The flower heads are about inches 

 across, the ray florets violet and disc florets yellow. — L. C. E. 



Bacterio-toxins in the Soil, The Non-persistence of. By H. B. Hutchinson 



and A. C. Thaysen {Jour. Agr. Set. vol. ix. Part 1 ; Aug. 1918). — The effect of 

 partial sterilization of soil, either by heat or by mild antiseptics, on its fertility is 

 well known, but the reason (or reasons) for it is not thoroughly established. 

 Of recent years several experimenters have claimed to have obtained evidence 

 of the existence of bacterio-toxins in the soil, and Greig Smith in particular, 

 working with Australian soils, has concluded that such toxins are present in soil 

 and adversely affect the number of bacteria. In connexion with work on Indian 

 soils, C. M. Hutchinson, also, has assumed that toluene increases the fertility 

 of soil by destroying its toxicity. The experiments of Greig Smith were made 

 on very dilute sodium chloride extracts of the soil examined. These extracts, 

 after being made germ-free by filtration, were divided into two portions, of which 

 one was untreated and the other heated. They were then inoculated with the 

 rather rare Bacillus prodigiosus. The results obtained showed a marked re- 

 duction after twenty-four hours in the number of cells in the untreated extract 

 and an increase in the heated extract. It was inferred that the untreated 

 extract contained toxins, that these caused the reduction in number of the 

 bacteria, and that the act of heating the extract destroyed the toxins and thus 

 allowed the organism to multiply. 



The authors of the present paper decided that it was desirable to repeat these 

 experiments on English soils, and six such soils were dealt with. The results were 

 that in each case there was at first a reduction in the number of bacteria in the 

 untreated soil, followed in three cases by recovery forty-eight hours after in- 

 oculation, after which increase in numbers took place. With extracts of the 

 three remaining soils there was no such recovery. The latter would therefore 

 appear to give some support to Greig Smith's conclusions. But if the falling 

 off was due to toxins the heated extracts should have shown improvement. 

 This was not so, however, for of the six soils the value of one extract waa main- 

 tained but not increased, while the remaining five showed reductions in number 

 of germs amounting, after seventy-two hours, to fourteen-fifteenths of those 

 < f the untreated extracts. Hence either lack of increase is not due to toxins. 



