404 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



When the process of nitrification is intense, the ordinary cocci (megalococci) 

 give rise to smaller cocci. These are set free and begin independent existence, 

 leaving the empty sheaths. They may later acquire a gelatinous coat, and 

 revert to megalococci. 



For staining these organisms, malachite-green and gentian violet were found 

 to be most effective. Preparations thus obtained show the jelly of the megalo- 

 cocci a deep purple colour, and the small cocci appear of a purple-black colour. 



The thermal death-point of the organisms studied was found to lie between 

 50° and 55 0 C.—R. J. L. 



Nitrogen-fixing and Nitrifying Organisms, Effects of Carbon Bisulphide and 

 Toluol upon. By P. L. Gainey (U.S.A. Jour. Agr. Res. xv., No. n, Dec. 

 1918, pp. 601-614). — Carbon bisulphide and toluol, when applied to soils in 

 sufficient quantities, will destroy Azotobacter group of organisms and check the 

 accumulation of nitrate nitrogen, and will destroy the nitrifying organisms. 

 The quantities necessary to produce such effects vary widely, and depend upon 

 the amount of moisture present. Other nitrogen-fixing organisms are not 

 destroyed by 10 c.c. of CS 2 or toluol, even when the moisture content of the soil 

 is high. There is no evidence in these experiments to show that treatment with 

 antiseptics stimulates the nitrifying organisms, and there is little evidence to 

 indicate a stimulative effect upon the ammonifying or nitrogen-fixing organisms 



A. B. 



New Plants (Rev. Hort. vol. xci. pp. 260-262; 2 figs.). — Columnea hirta 

 flourishes in hanging baskets in a warm house. It bears large scarlet flowers 

 spotted with yellow. C. hirta glabra is distinguished from the former by its 

 beautiful bronze foliage. 



Feijoa Sellowiana is hardy in the South of France. It bears magnificent 

 red flowers with bright carmine stamens. Loropetalum chjnense is hardy. In 

 early spring it is covered with white flowers. 



The following varieties of Hydrangea hort en sis are suitable for forcing : — 

 ' Amazone,' white fimbriated ; ' Etincelant,' dwarf, bright carmine; ' Satinette,' 

 carmine red ; ' Trophee,' dark carmine. 



The following are hardy: — Adinidia purpurea, climber with white flowers 

 and purple fruit ; Dipelta floribunda is covered in spring with white tubular 

 flowers ; Pyracantha crenulata, from Yunnan, red berries ; Viburnum rhyti- 

 dophyllum, evergreen ; V. betulifolium, large corymbs of small white flowers 

 and cherry-red berries ; Deutzia crenata candidissima plena and D. Vilmorinae 

 are the parents of D. c. macrothrysa (very floriferous), D. c. mirabilis (milk white), 

 and D. c. staphyleoides, which has large flowers resembling Staphylea. 



Hybridization of Philadelphia microphyllus by P. coronarius and P. grandi- 

 florus yielded ' Coupe d'argent' with white flowers like a single rose ; ' Girandole,' 

 double ; ' Bicolore,' white with purple marks ; ' Nuage,' rose-white flowers with 

 pink centre slightly fimbriated ; ' Sylvanie,' white with pale pink centre. 



Diervilla ' Profusion ' is a hybrid from D. japonica. Early in May the shrub 

 is covered with panicles of carmine pink flowers. 



The lilac ' Edith Cavell ' is double white ; ' Paul Thirion ' wine-coloured ; 

 ' Maurice Barres ' is one of the most beautiful and floriferous lilacs, remarkable 

 for large lilac-blue panicles ; ' Mont Blanc ' is the finest single white ; ' Saturnale 

 Precoce,' single bluish mauve ; ' Vesuve,' single purple. 



Recent introductions from China are Syringa Wilsonii, a large shrub with 

 pale pink flowers ; S. Sweqinzowii superba, pale pink with pleasant perfume ; 

 and 5. reflexa, pink. — S. E. W. 



Oenothera rubrinervis, A Half-Mutant. By Hugo De Vries (Bot. Gaz. 

 vol. lxvii., No. 1, Jan. 1919, pp. 1-26). — The genetic constitution of Oenothera 

 rubrinervis is discussed and the experimental evidence detailed.— R. J. L. 



Onion Bulbs, White Rot Disease of. By A. D. Cotton and M. N. Owen 

 (Jour. Min. Agr. vol. xxvi. No. 11, Feb. 1920). — A disease causing considerable 

 damage to onion crop, which, however, until recently, has not attracted serious 

 attention. The fungus has been isolated and identified as Sclerotium cepivorum, 

 described by Berkeley in 1841, and is quite distinct from Sclerotinia bulborum 

 and Botrytis cinerea, both of which have been regarded as the cause of the trouble 

 in question. 



It has been popularly called Dry Rot, White Rot, Mouldy Nose, and in the 

 North, erroneously, " Mildew." 



Onions become attacked by White Rot from contaminated soil, and usually 

 first show signs of the disease at end of May or early in June. The leaves wilt 

 and turn yellow, the oldest leaves first, and ultimately collapse, when plants 



