NOTES AND ABSTRACTS. 



523 



to the view that mutants are the result of crossing (heterozygosis). The author 

 raised mutants for a self-fertilizing species of Oenothera. 



It may be observed that many wild plants have varieties, although continually 

 self-fertilized, as the knotgrass {Polygonum aviculare) described by Hooker in his 

 " Student's Flora." Again, all the plants of the desert near Cairo have varied to 

 become cleistogamous, since there are no insects there. 



The author gives eight conclusions. The important are : (1) Oe. pratincola, 

 a self-pollinating species, is in a mutating condition comparable with that of Oe. 

 Lamarckiana. (5) The mutation ratio cannot be explained on Mendelian grounds. 

 (8) The phenomena of Oe. Lam., Oe. biennis, and Oe. pratincola cannot be 

 attributed to heterozygosis. — G. H. 



Nasturtium Wilt caused by Bacterium Solanacearum. By M. K. Bryan 



(Jour. Agr. Res. iv. pp. 451-458, August 1915 ; plates). — A disease of Tropaeolum 

 majus characterized by the leaves being mostly wilted, yellowed, or dead, and the 

 stem having a peculiar translucent or water-soaked appearance, allowing the 

 vascular bundles to show as darkened streaks beneath the unbroken epidermis. 

 When cut across, a greyish white viscid slime exudes from the bundles, and 

 becomes brown on standing. Inoculation and cultural experiments established 

 the identity of the causal organism as Bacterium Solanacearum. The bacteria 

 may enter through wounded roots or shoots, or through the stomata. Potato, 

 egg plant, Ageratum, Verbena, tobacco, tomato, pea-nuts, and pepper are all 

 liable to be attacked. — F.J. C. 



Naturalization, Experiments in (Rev. Hort. d'Alg., No. 1, Jan. 1914, p. 6). — 

 Notes on the behaviour of some exotic trees and plants of economic importance 

 which are being planted in experimental gardens in Algeria. 



These include the coffee plant, camphor tree, Casuarina, Vanilla, rice, 

 Sarsaparilla, yam, dec. — M. L. H. 



Nitrogen- fixing Power, Effect of Moisture Content of a Sandy Soil on its. 



By C. P. Lipman and L. T. Sharp (Bot. Gaz. vol. lix. p. 402). — From the tables 

 of experiments the conclusion is drawn that when both aerobic and anaerobic 

 bacteria are present the greatest fixation of nitrogen will occur at a moisture 

 content very favourable for the most active forms of nitrogen-fixing bacteria. 

 In the soil used it would appear that the aerobic forms do best with a 20 per cent, 

 moisture content. At higher percentages of moisture up to 24 per cent, the 

 anaerobic forms become much more active, while the aerobic forms are depressed 

 in their nitrogen-fixing powers. — G. H. 



Nitrogenous Fertilizers, Determination of their Availability. By C. B. 



Lipman and P. S. Burgess (U.S.A. St. Bd., Berkeley, California, Bull. 260; 

 19 pp.). — A discussion of the best form in which nitrogen may be added to 

 the arid soils of California, and the conclusion is reached that for such soils low- 

 grade fertilizers such as cotton-seed meal, bone manure, sewage sludge, &c, are 

 most economically transformed by the soil flora. — E. A . Bd. 



Norway Pine in the Lake States. By Theodore S. Woolsey, Jr., and Herman 

 H. Chapman (U.S.A. Dep. Agr., Bull. 139, December 4, 1914).- — Norway pine, or 

 red pine (Pinus resinosa) as it is sometimes called, is a tree whose importance is 

 certain to increase. Even now it is important commercially. From the stand- 

 point of forest management, however, its special value lies in the fact that it 

 makes better growth on poor soils than does its associate, white pine ; it prunes 

 itself of branches earlier, is more hardy, is freer from injury by insects or fungi, 

 and ranges over as wide a territory. 



The better quality Norway pine wood is soft, light, moderately strong and 

 tough, fine, and straight-grained. It is easy to work, but is not durable in contact 

 with the soil. The best grades are cut from trees of rapid growth, on low, moist, 

 rich soil, and exhibit very littlefcontrast between early and late growth. Lumber 

 cut from slow-growing trees, on dry, sandy soils, is redder in colour, more resinous, 

 and somewhat harder and more durable than the other. There is also afmarked 

 difference between the weight and quality of lumber cut'from young stands and 

 from mature timber, due to the percentage of sapwood in the former. : : - 



•-Norway pine is adapted for most of the uses to which white pine is put. It 

 was first cut in. Maine^and- Canada: for shipbuilding' material, such as decking, 

 planking, spars, and masts. It is used locally for bridges, though it is distinctly 

 inferior to long-leaf pine and Douglas fir for the purpose. Perhaps it is in widest 

 demand for dimension stuff and for ordinary house construction. '. The lower 

 grades and smaller sizes are consumed largely by the box trade for crates and 



2 m 2 



