184 



The Plant World. 



tains many fine hand-made cuts showing characteristic forms 

 and habitats of such trees as European larch, Roman cypress, 

 Lombardy poplar, English oak, cedar of Lebanon, Deodar cedar, 

 Norway spruce, silver fir, yew, beech, and hornbeam. Prac- 

 tically all the full-page illustrations, as well as most of the smaller 

 ones, are drawings instead of photographic cuts that so often 

 do not illustrate, of which fact writers of technical and popular 

 publications can well afford to take notice. In the second half 

 of the book trees are classified according to their shapes. The 

 book is written in the same clear, concise style that characterizes 

 the other volumes, and hence will be as useful to the amateur as 

 to the professional botanist. Of this valuable series of books, 

 volume I deals with buds and twigs, volume II with leaves, 

 volume III with inflorescence and Mowers, volume IV with fruits, 

 while the present and last one treats of form and habit of trees 

 These books are already so well known that little comment is 

 necessary, having found their way into the hands of many per- 

 sons interested in trees and forestry. 



J. J. Thornber. 



In experiments of Osterhout, reported in the Jahrb. f. 

 wissensch. Botanik, when seedlings of wheat were grown in a 

 mixture of 400 cc. XaCl and 30 cc. KG, the roots made nearly 

 three times as great a growth in length as in the pure solution of 

 either of those salts, both of which were shown to be poisonous 

 when employed alone. A like relation w r as observed between 

 salts of sodium and magnesium. The spores of Botrytis cinerea 

 failed to grow in a solution of either sodium or magnesium 

 chloride, but grew well in a mixture of the two, the best results 

 being obtained with a mixture of lOOcc. sodium chloride with 

 lOcc. magnesium choride. Calcium also hinders the poisonous 

 action of sodium. The antagonism between the chlorides of 

 sodium and calcium is much greater than between those of 

 sodium and potassium or sodium and magnesium. The ex- 

 periments were repeated on different plants, w r ith the substitu- 

 tion of nitrates for chlorides and in soil as well as in water 

 cultures, with entirely similar results. Like results have also 

 been obtained by Loeb and Ostwald in their work with various 

 animals, The experiments suggest a combination with some 



