236 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



fertilizers which will supply nitrogen, phosphate, and potash at the 

 rates of about 30, 65, and 50 pounds to the acre respectively (p. 26). 

 The question of cover crops versus tillage is also discussed, and its 

 bearing upon systems of manuring (pp. 21 and 22). — A. P. 



Arsenical Compounds upon Apple Trees, A Preliminary 

 Report on the Effects of. By D. B. Swingle and H. E. Morris 

 {Phytopathology, vol. i. pt. 3, pp. 79-93; June 1911). — It has been 

 reported by some observers that arsenical compounds damage fruit trees 

 when used as sprays, while others have denied that any such damage 

 was done. A considerable series of experiments was arranged by the 

 authors, who conclude that 



1. Serious injury to apple trees may, under certain conditions, 

 result from application of the so-called " insoluble " arsenical insecti- 

 cides. 



2. Among the conditions that favour this injury, recently made 

 wounds through the outer bark are highly important. 



3. Functional lenticels and dormant buds also permit the absorption 

 of arsenical compounds in solution. 



4. The corky bark is highly protective and does not readily become 

 disintegrated by the action of arsenical compounds. 



5. It is not safe to cut off water sprouts from the bases of trees in 

 early spring and permit the arsenical washes now in use to accumulate 

 about the unprotected wounds the same season. 



6. White lead paint applied to these wounds will practically protect 

 them even if put on just before the arsenicals are applied. 



7. The most noticeable symptoms of rapid arsenical injury through 

 the bark is discoloration of bark and outer wood, often following 

 definite lines up and down the stem, and a dull spotting of the leaves 

 followed by waiting, shrivelling, and drying. 



8. It is not improbable that the injury is due more to soluble im- 

 purities than to the slight solubility of the compounds themselves. 



9. If this is the case the remedy for the alleged arsenical injury lies, 

 not in discontinuing the use of arsenical insecticides, but in securing 

 grades of higher purity. 



10. Arsenic trisulphide does not promise to be more safe when ap- 

 plied to the bodies of trees than the arsenical insecticides now in com- 

 mon use. 



11. Zinc arsenite gave practically no injury under the most severe 

 conditions of the tests. — F. J. C. 



Alcohol from Tunas and other Sources, Denatured. By 



Messrs. Hare, Mitchell and Bjerregaard (U.S.A. Exp. Stn., New 

 Mexico, Bull. 72, 1909). — Alcohol being much used, when denatured, 

 for industrial purposes, many plants and farm products have been 

 utilized as its source, amongst others the Tiuia, or Prickly Pear. 



The word alcohol, as used here, means Ethyl, ordinary or grain 

 alcohol, sometimes called spirits of wine. It is produced by 



