Physiologie. 169 



formation of nitrates and ammonia. It is presumed that the hydro- 

 gen is kept in the nascent State by the platinum, and reduces the 

 nitrate directly. The platinum hydroxide in turn splits into platinum 

 and hydrogen peroxide, the latter decomposing to water with the 

 liberation of ox}^gen. The ultra violet light of the quartz mercury 

 vapor lamp reduces potassium and calcium nitrates with remarkable 

 ease and the same action takes place more slowly in diffuse sun- 

 light. The reduction of these nitrates results in a decidedly alkaline 

 Solution. A brief discussion of the Steps in the appropriation of 

 carbon dioxide and its picturing follows. Moore. 



Swingle, D. B. and H. E. Morris. A preliminary report on 

 the effects of arsenical Compounds upon apple trees. 

 (Phytopathology. I. p. 79—93. pl. 16—17. Jul. 1911) 



From experiments with various arsenic Compounds applied 

 directly to the branches and crowns of trees by means of absor- 

 bent cotton and gauze bandages the following conclusions were drawn. 



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

 result from applications of the socalled "insoluble" arsenical in- 

 secticides. 



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

 wounds through the outer bark are highly important. 



3. Functional lenticels and dormant buds also permit the ab- 

 sorption 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 for orchardists to cut off water sprouts from the 

 bases of trees in early spring and permit the arsenicals now used 

 as insecticides 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 are a discoloration of bark and outer wood, often 

 following definite lines up and down the stem, and a dull Spotting 

 of the leaves followed by wilting, shriveling and drying. 



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

 impurities than to the slight solubility of the Compounds themselves. 



9. If such should prove the case, the remedy for the alleged 

 arsenical injury to crows (excepting perhaps in alkali soils) 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 

 applied to the bodies of trees than the arsenical insecticides now 

 in common use. 



11. Zinc arsenita gave practically no injury under the most 

 severe conditions of the tests. If this Compound bears up as well 

 during future tests and proves a satisfactory insecticide, it may 

 become generally recommended, especially if it does not prove 

 practicable to get grades of Paris green and lead arsenic that will 

 not injure through wounds. Moore. 



Tunmann, O., Ueber angewandte Pflanzenmikrochemie 



