226 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
where the production of manure is large, and (5) the fact that compactness 
and high moisture content, which render the trap most effective, are conditions 
which tend to preserve the value of the manure. — F. G. A. 
Humogen, Experiments with. By M. F. F. Sutton {Bull. 8, Messrs. Sutton, 
Reading, June 1917)- — A series of experiments with humogen (bacterized 
peat), in comparison with other manures, was started in 191 7. Some adverse 
results are recorded, and in general the results were not in favour of humogen, 
which also varied in its effect according to the source from which it was 
obtained. — F. J. C, 
Hybridization, Sterility as the Result of Hybridization and the Condition 
Of Pollen in Rubus. By C. S. Hoar (Bot. Gaz. vol. lxii. Nov. 1916, pp. 370 ; 
with plates x.-xii.). — The author draws the following conclusions : — • 
1. Sterility of pollen has long been recognized as a criterion of hybridization. 
2. Crosses between distinct species have long been known to be more or less 
sterile and to behave differently from crosses between more closely related forms 
or varieties. 
3. True species when crosses do not, in most cases, follow the laws of Mendel, 
but tend rather to blend to form more or less constant types, often systematically 
recognized as species. 
4. Many species of the Angiosperms are species in a very different sense from 
those of the lower plants and of the Gymnosperms in particular. 
5. In some cases they are natural hybrids which have external characteristics 
distinct and constant enough to have specific rank from a systematic standpoint. 
6. Although these species may be distinct from the systematic standpoint, 
yet they must be treated in a different manner from the standpoint of the 
evolutionist and the plant breeder. 
7. Finally, the species of the genus Rubus, as shown from the pollen con- 
dition and also from external characters, clearly hybridize very frequently in 
nature, giving rise to constant forms often recognized as true species. — R. J. L, 
Hymenanthera crassifoiia. By F. G. Preston {Irish Gard. xii. Jan. 1917. 
p. 5 ; fig.). — A desirable shrub for garden purposes, but very seldom seen. Pro- 
duces white berries, of dense semi-evergreen habit and 4-5 feet high. — E. T. E. 
Injection Experiments on Plants. By Yasutaro Yindo {Jour. Coll. Sci. 
Tokyo, xxviii. pt. 6, May 191 7 ; plates). — A large number of experiments on 
growing plants performed with the object of ascertaining the distribution and 
rate of conduction of substances injected into various tissues are recorded. 
The author found the movement of substances dependent to a great extent 
upon the transpiration current, and mostly in an upward direction. There 
was, however, some downward diffusion, and to a much slighter extent lateral 
diffusion. It is not clear whether downward. diffusion took place mainly along 
the xylem or along the phloem, but it seems evident that the demand for water 
may cause a downward flow along the xylem vessels and away from the leaves 
under certain conditions. Lithium nitrate solutions were generally used, but 
staining solutions showed that individual bundles preserve their identity through 
a great part of the plant. — F. J. C. 
Insecticide, Warm Water as. By P. Viala {Le Jard. vol. xxxi. p. 156). — Vines 
and orchard trees may be freed from pests by watering the foliage with water 
at a temperature of I50°F. — S.E. W. 
Iris arizonica, spec. nov. By W. R. Dykes {Gard. Chron. Feb. 3, 191 7, p. 
45; with Latin diagnosis). — A distinct species allied to /. longipetala, raised by 
Mr. Dykes from seeds attached to a herbarium specimen from Arizona. — E . A . B. 
Lace-wing Fly, Calif ornian Green. By V. L. Wildermath {Jour. Agr. Res. 
vi. pp. 515-526; July 1916 ; figs.). — An account is given of the life-history 
and habits of the Calif ornian lace-wing fly {Chrysopa calif ornica). It is in the 
main similar to that of the common British species, and is found to devour 
between 300 and 400 aphides during its larval existence. — F. J. C, 
Leopard-moth : a Dangerous Imported Insect Enemy of Shade Trees. By 
L. O. Howard and F. H. Chittenden {U.S.A. Dep. Agr., Farm. Bull. 708, 
February 14, 191 6). — The leopard-rnoth, like so many other dangerous pests, 
is a European species which has been accidentally introduced into the United 
States in comparatively recent years. Its Old-World distribution, as recorded, 
