424 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
utilizing all the nutrient present (pp. 37-58). Where the soil available per 
plant is not kept constant, as happens in the case of plots of plants in a field, 
the outside rows have been found to be stronger than the inside up to an excess 
of 100 per cent., a superiority not attributable, as generally supposed, to the 
extra food procurable, but to the fact that they were less affected by the toxic 
action of the neighbouring plants than were the inner rows (pp. 59-68). — A. P. 
Plants, The Upward Translocation of Foods In Woody. By O. F. Curtis 
(Amer. Jour. Botany, vol. vii. Nos. 3 and 7, March and July 1920, pp. 101-124, 
286-295). — It is a general belief that in shrubs and trees there is a storage of 
organic matter in the lower part of the trunk and in the roots, and that, as 
growth starts in the spring, this food becomes soluble and passes upward through 
the xylem to the growing shoots and leaves. In order to determine definitely 
whether the upward translocation^ of food takes place primarily through the 
phloem or xylem, the author conducted a series of experiments with Philadeiphus 
pubescens, Pyrus Malus, Ligustrum ovalifolium, Crataegus sp., Acer Saccharum, 
and Fagus grandifolia, and arrives at the following conclusions : 
Defoliated stems, from which a ring of tissue extending to the cambium is 
removed, cease growth. This cessation is due to the inability of the xylem to 
carry the necessary food which is required, not merely for the supply of energy and 
building fresh tissues, but to increase the osmotic concentration of the tissues to 
enable them to absorb water. This food consists of carbohydrates. If the stem 
above a ring is not defoliated the leaves are able to supply sufficient food to allow 
for considerable growth. If dormant stems are ringed the growth above the 
rings ceases soon after the starch supply is depleted and the greater the supply 
of starch above a ring the longer will growth continue. The carbohydrates 
stored in the xylem below the ring cannot be removed through' the xylem but 
are transferred radially to the phloem, where they may be carried downward if 
there is no second ring below. The carbohydrates of the xylem between two 
rings remain there at least for some time after those above the upper ring and 
those below the lower ring have been mostly removed. Although large amounts 
of carbohydrates are stored in xylem tissues, there is no appreciable longitudinal 
transfer of sugars through these tissues. — A. B. 
Pleurothallis grandis Rolfe {Bot. Mag. t. 8853, Sept. 1920). — A native of 
Costa Rica, with large curiously striped flowers, requiring an intermediate house 
and thriving in peat and sphagnum. — F. J. C. 
Pleurothallis punctulata Rolfe {Bot. Mag. t. 8839; March 1920). — An 
epiphytic species from New Granada of which only one plant is known. Its 
curious flowers, through the twisting of the petiole, face the lower side of the 
grey- green leaves. It flowered along with Masdevallias at Kew. — F. J. C, 
Plum Trees, A "Wither Tip" of. By H. Wormald, M.Sc, A.R.C.Sc. {Ann. 
Appl. Biol. vol. V. No. I, July 1918, pp. 28-59 ; figs.). — [a) General observations ; 
(&) the fungus under heads of — annual cycle, cultural studies, dimensions of the 
conidia, and identity of the fungus ; (c) inoculation experiments — of plum leaves, 
plum flowers, immature plums on trees in the plantation, and of apple flowers. 
The experiments show that the particular strain of Monilia cinerea obtained 
from plum twigs is less virulent as an apple parasite than the apple blossom 
strain itself. Control measures suggested are removal of diseased twigs and 
fruit, and spraying with a solution of i per cent, caustic soda and i per cent, soft 
soap as a winter wash ; but sprays are not recommended. Removal and burning 
of diseased fruit and twigs is. however, imperative. 
A bibliography is appended. — R. C. S. R, 
Podophyllum Emodi var. chinense Sprague {Bot. Mag. t. 8850 ; June 1920). — 
Distinguished from the type by its much-divided leaves and rose-coloured 
flowers. Native of Kansu and re-introduced by Mr. Farrer. — F. J . C. 
Poisonous Plants. By J. H. Maiden {Agr. Gaz. N.S.W. vol. xxx. p. 553). — 
Dichopogon Sieherianus and the Wild Onion {Bulbine bulbosa) are suspected of 
poisoning sheep. — 5. E. W. 
Pollination, Almond. By W. P. Tufts {U.S.A. Exp. Stn. Calif., Bull. 306, 
figs.). — Seventeen varieties of the Almond were tested, all of which proved to 
be self-sterile. Certain varieties were also found to be intersterile. A short 
list of pollenisers is given for a few varieties. Bees were found of great benefit 
in assisting pollination, and a method of arranging the varieties in the orchard 
to facilitate cross-pollination is described. — A . N. R. 
