BOOKS AND CURRENT LITERATURE 19 



in which the investigation has been begun and carried out, and the 

 thorough treatment of the whole result of the investigation. As true 

 naturalists the writers have not concealed the shortcomings in their 

 investigation — -let us hope that still existing problems will provoke 

 continued publications on the Salton Sink. — Ove Paulsen, Copenhagen. 



Periodicity in Trees, — Rhythm and periodicity may not be so 

 much a part of the life of the plant as has been taken for granted by 

 physiologists. The beech has been cited for many years as imperturb- 

 able in its resting period, and not to be awakened during the winter 

 time by any high temperature exposures, ether threatment, etc. Pro- 

 fessor Klebs 1 of Heidelberg has been able, however, to maintain the 

 European beech (Fagus silvatica) in continuous growth during the 

 winter, and concludes that the countless experiences of the species 

 with alternating favorable (summer) and unfavorable (winter) seasons 

 have made no permanent impress on the organism in the way of an 

 acquired rhythm. Confirmatory results with oak, ash, and hornbeam 

 were obtained. Professor Klebs used a small enclosed chamber in a 

 dark room, illuminated by tungsten lamps of a total intensity of 200 

 candle power, and the entire dark room with 1000 candle power. 

 Moisture and temperature control and registration were secured. — 

 D. T. MacDougal. 



Tropical Silviculture. — Under the title of Sylviculture in the 

 Tropics, Broun 2 incorporates in one volume a discussion of the problems 

 of silviculture as applied to the tropics. The author frankly states 

 that had he undertaken the publication on his own accord he would 

 have restricted its application to the portions of the tropics and of the 

 sub-tropics in which he had gained his experience. The author's work 

 in India, Ceylon and Soudan is utilized to make many practical appli- 

 cations. Aside from this the publication does not offer anything new 

 to the art of silviculture. — H. N. Whitford, Canadian Commission 

 of Conservation. 



1 Klebs, G., tjber das Treiben der einheimischen Baiime, speziell der Buche. 

 Abh. d. Heidelb. Akad. d. Wiss. Math-Naturw. Kl. 3 Abhandl. 1914. 



2 Broun, A. F., Sylviculture in the Tropics. Pp. 309, figs. 96. Macmillan 

 and Company, 1912 ($3.00). 



