CURRENT LITERATURE 



BOOK REVIEWS 



Injury by smoke 



Dr. A. WiELER^ has written a volume upon the eflfects on vegetation of sulfur 

 (?ioxid, the most mjurious constituent of smoke.* The subject of smoke injury to 

 agncultural and forest crops has long been of importance in Europe, and is now 

 beginning to attract attention in this country, where, with the extension of agri- 

 culture into semiarid mining regions and the increased interest in forestry, some 

 means of restraining injur}' to crops or some basis for adjusting damages becomes 

 more and more necessary\ 



The first chapter of the book is devoted to the demonstration of the presence 



of SO2 in the leaves of plants injured by smoke. For this the author relies on 



the method of Wixdisch, which revealed the presence of SO3 in leaves of ivy even 



14 days after fumigation. Numerous analyses from smoky districts showed SO2 



m the leaves in varying amounts. The analy^s do not show any definite relation 



between the amount of SOa present in the leaves and distance from the source of 

 smoke. 



In the second chapter it is shown that, contrary to the view of vox Schroeder 

 and Reusz, SG^, like other gases, enters only through the storaata. Leaves whose 

 stomatal surfaces were coated showed no injury when exposed for several hours 

 to comparatively strong concentrations of the gas. In ver)* young leaves and in 

 leaves whose stomata are permanently closed, the gas penetrates the cuticle. 



grater part of the book, discusses 



be 



gas 



all cannot 

 iv both its 



tissues 



prod 



come into play. Two kinds of injury are distinguished, the acute and 

 the chronic. The acute form is rare and occurs only in the immediate vicinity of 

 the source of smoke, where the concentrations of SO^ are sufficiently high to kill 

 the tissues directly. Yet experiments on the resistance of various organs show 

 that the concentration of gas necessary to produce the acute form of injury is much 

 greater than that found in smoke-injured regions, and the great individual dilFer- 

 ^nces shovm tend to obscure the results. To find an explanation of the chrome 

 injun^^ which is the more common and more difficult to recogoi^ and account 

 for, the effect of dilute mixtures of the eras were studied. Even under uniform 



^ WnxER, A., Untersuchungea uber die Knwirkung schweffiger Saure airf c 

 Pflan^n. 8vo. pp. vii + 427. ^^1. ig. BerHn: Gebruder Bomtraeger, 1905- i/z2. 



=* The importance of this work justifies the publication erf a review long after 

 was due,— 



