410 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
from the rusty spots on the apple leaves are carried by the wind to the cedar 
trees, where galls develop twenty months later. These galls yield spores which 
attack the apple trees, causing the leaves to fall off. Hawthorns and crabs are 
also attacked. Spraying has not been successful ; the only remedy appears to 
be the removal of the cedars. — 5. E. W. 
Celery Fly, Oviposition in the. By T. H. Taylor {Ann. AppL Biol. vol. v. 
No. I, July 1918, pp. 60-61; I text fig.). — The habits of the celery fly are 
described, with special reference to the egg-laying process and the burrowing 
of the larva in the leaf tissues. — R. C. S. R. 
Chemotropic Responses of Insects, Field Experiments on the. By A. D. 
Imms and M. A. Husain (Ann. App. Biol. vol. vi. No. 4, April 1920, pp. 269, 
292; I fig.). — This paper is intended as a basis for further research into the 
chemotropic responses of insects. 
A bibliography and an historical review are given of the early papers dealing 
with this subject; the author's experiments are detailed. 
Few insects besides diptera were captured, probably on account of the small 
size of the traps used. Beer and cane m.olasses proved to be the most success- 
ful baits. The authors point out the difficulties in this research, and the many 
factors to be taken into consideration. — G. F. W. 
Cherry Tree Grafting. By P. Lecolier {Rev. Hort. vol. xcii. pp. 161-162). — 
Whip-grafting on the wild cherry is the most rapid method of renewing the 
cherry orchards destroyed by the Germans in Belgium. The operation should 
be carried out in the second half of September. — S. E.W. 
Chestnut Trees, Effects of Injection of Chemicals upon. By C. Rumbold {Amer. 
Jour. Bot. vol. vii. Nos. i and 2, Jan. and Feb. 1920, pp. 1-20, 45-56 ; 2 plates). 
— These experiments were undertaken in the hope of discovering some remedy for 
the chestnut bark disease {Endothia parasitica Murr.) in eastern U.S.A. Ordinary 
methods of spraying and soil disinfectants were apparently without avail in 
checking this disease. A large number of substance^, organic and inorganic, 
were injected into 156 ' Paragon ' chestnut trees during the growing season, and 
it was found that solutions of organic compounds were more readily " absorbed " 
than inorganic solutions, and usually the more concentrated the solutions of 
chemicals the more readily were they absorbed by the trees. In S.W. Pennsyl- 
vania, June was the best month for injection, as far as the rate of intake was 
concerned. The injected solution as a rule passed through the vessels of the 
youngest annual rings up and down the trunk in a zone whose width was usually 
little more than that of the injection hole. As a rule the injection was not 
harmful to the trees in the case of the alkali metals and organic compounds, 
but the injection of heavy metals was detrimental. A watery extract of chestnut 
blight canker was harmful, but healthy bark extract was not. Many of the 
bases produced characteristic colorations of the leaves. It was found that 
solutions of lithium salts injected in the spring months may have an effect upon 
the blight, in that the growth of the canker was checked and healthy callus was 
formed over the canker. Further experiments, however, are necessary to obtain 
conclusive results. — A. B. 
Chrysanthemums, Varieties of. By Hort {Le Jard. vol. xxxiv. pp. 53-55, 
61, 62, 70, 71 ; 4 figs.). — A list of the best varieties of Chrysanthemums classified 
in fourteen groups recommended by a committee of French specialists. — S. E. W. 
Citrus, Effects of Alkali on. By W. P. Kelley and E. E. Thomas {U.S.A. 
Exp. Stn. California, Bull. 318, Jan. 1920, pp. 304-338 ; 2 figs.). — It is generally 
believed that citrus trees are especially sensitive to alkali, and this is thought to be 
due to excessive concentration of the alkali. The symptoms of alkali injury are 
a yellowing of the margins and tips of the leaves, followed by a shedding of the 
entire foliage. ' Navel ' oranges are more sensitive than ' Valencia,' and ' Eureka ' 
lemons more sensitive than ' Lisbon.' Generally lemon trees are more sensitive 
than orange trees. It was found that some irrigation waters were highly 
charged with alkali, and various tables are issued showing the analyses of some 
of the irrigation waters used in California. The use of mountain water is advo- 
cated and a plentiful supply can be obtained by use of dams and reservoirs. — A . B. 
Citrus Fruit Improvement. By A. D. Sham el, L. B. Scott, C. S. Pomeroy, 
and C. L. Dyer {U.S.A . Bur. PI. Ind., Bull. 813, June 1920, pp. 1-89 ; 22 figs.).-- 
The lemon {Citrus Limonia Osbeck) is largely grown in California, which State is 
responsible for practically 90 per cent, of lemons produced in the United States. 
