150 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY, 



Agave bracteosa (Bot. Mag. tab. 8581). — N. Mexico. Nat. Ord. Amaryllida- 

 ceae, tribe Agaveae. Shrub, almost stemless. Leaves about 50 in a rosette, 

 2 h inches wide, with a long acuminate tip. Pole 6 feet high, spike 2 feet long. 

 Perianth green, white-margined. — G. H. 



1. Ammonifying Efficiency of certain Colorado Soils, The. By W. G. 

 Sackett. 2. Algae in some Colorado Soils. By W. W. Robbins (U.S.A. 

 Exp. Stn., Col., Bull. 184 ; 35 pp. ; 4 plates). — A number of soils in the Colorado 

 districts have so great a power of ammonifying various organic materials as to 

 produce nitre-burning in many orchards, or even to destroy them. 



Tables are given showing the effect of such soils on various organic fertilizers. 

 The second part deals with the algae present in the soils, with four coloured plates 

 of the species. — C. P. C. 



Apple Trees, Canker. By G. P. Darnell-Smith (Agr. Gaz. N.S.W. vol. xxv. 

 pp. 1037-1044 ; 9 figs.). — Canker is due to injury of the cambium, which may 

 be caused by frost, exposure to excessive heat of the sun, or to the action of 

 fungi. , Painting the tree with a thick coat of hme-wash is a remedy for sun 

 scald. Bitter Rot or Ripe Rot is caused by Gloeosporium fructigenum, and Apple 

 Blotch by some form of Phyllosticta ; in either case prune out and burn all 

 cankered twigs and spray with Bordeaux mixture. In canker on branches too 

 large to cut out they are scraped and painted over with thick Bordeaux paste. 

 Nectria Canker (N. ditissima) attacks the bark, often girdling small branches. 

 It is not met with in orchards free from American Blight. Blight (Bacillus 

 amylovorus) attacks the blossoms, twigs, and fruit, causing the leaves to shrivel 

 and the blossom to turn brown. Small drops of a viscous liquid exude on the 

 twigs and petioles. Lime-sulphur spray is the best remedy for mildew. There 

 does not appear to be any cure for Crown Gall, which is caused by Bacterium 

 tumefaciens. — S. E. W. 



Apples, Technical Descriptions of. By J. K. Shaw (Mass. Agr. Exp. Stn., 

 Bull. 159, Dec. 1914 ; 14 figs.). — This is a compilation from various sources of 

 the description and selection of characters useful in describing apples. A new 

 feature is the photographs of leaves, illustrating their shape and pose. Other 

 than this the matter has been fully dealt with in many well-known works of 

 reference. — E. A. Bd. 



Aquatics (Rev. Hort. Beige, March and Ap. 30, 1914; plates). — Some 

 notes on the cultivation of Nymphaeas and Nelumbiums. — M. L. H. 



Armillaria mellea, The Death of Chestnuts and Oaks due to. By W. H. 



Long (U.S.A., Dep. Agr., Bur. PI. Ind., Bull. 89, May 1914, pp. 1-9; 2 

 plates). — This fungus, under favourable conditions, can become an active parasite 

 on chestnuts and oaks, destroying not only the crowded trees in the forest, but 

 also those growing under more favourable conditions. It usually occurs at the 

 base of the trees, and the black lace-like mycelium (rhizomorphs) spread down- 

 wards to the roots and upwards under the bark of the stems. This weakens the 

 tree and ultimately destroys it completely. Of the chestnuts, 21 per cent, have 

 been destroyed by the disease ; while 27 per cent, of the oaks were killed from 

 similar attacks in Chenango County, New York State. — A. B. 



Azalea 4 Mad. Petrick * superba (Rev. Hort. Beige, Feb. 1914, p. 52). — Anew 

 variety of A. indica, said to be a valuable novelty from its early flowering and 

 perfect habit of growth. — M. L. H. 



Azores, Notes on the Native Plants. By H. B. Guppy (Kew Bull. 1914, 

 p. 305). — The flora of the slopes of the mountain of Pico is reviewed, with notes 

 on the zones of vegetation. — F. J. C. 



Bacterial Activity in Soil as a Function of Grain-size and Moisture 

 Content, The. By Otto Rahn (U.S.A. Exp. Stn., Michigan, Tech. Bull. 16 ; June 

 1912). — The effects of grain-size and moisture content on bacterial activity is 

 herein discussed. The author deduces that the larger the grain-size the higher 

 the number of bacteria, and necessarily the increase in ammonia compounds. 



It is also found that both the aerobic and anaerobic types thrive best in 

 soils of large grain-size containing the optimum amount of water, anaerobic 

 bacteria being more favoured by increasing quantities of water even to a water- 

 logging. Sands require far less moisture for the highest development of bacteria 

 than clay or loamy soils. — C. P. C. 



