BOOKS AND CURRENT LITERATURE 



Xerophily. — The inquiry as to what plants shall be designated 

 xerophytes was made about a year ago by Kamerling 1 and has been 

 more recently raised by Miss Delf. 2 The latter author has made a very 

 careful answer to the question, showing that xerophytes have been de- 

 fined in turn on habital, anatomical, and physiological evidence. 

 Kamerling attenuated to establish a purely physiological criterion for 

 xerophily, based upon transpiration behavior. He' measured the tran- 

 spiration from severed shoots not supplied with water, a method which 

 possesses the lowest grade of experimental value and could be useful 

 only in the differentiation of an Impatiens and an Opuntia. Miss 

 Delf repudiates the methods of Kamerling, and she furthermore re- 

 jects any attempt to give a purely physiological definition to xerophily. 

 In such rejection she would doubtless include the suggestion of Bakke 3 

 that xerophily be defined in terms of the transpiring power of leaves, 

 as measured by hygrometric paper. "It is clear," states Miss Delf, 

 "that xerophily cannot be adequately defined in terms of habitat, of 

 anatomy, or of physiology alone. It is rather a natural conception in- 

 volving the total reaction of plant to environment." We have used 

 the term "xerophyte" for 93 years and are now attempting to sort out 

 the particular plants which belong in this category. Kamerling re- 

 jected the anatomical claims of Casuarina and Sarothamnus scoparius 

 as xerophytes, and also the claims of mosses and lichens, in spite of their 

 ability to withstand desiccation being greater than that of any flowering 

 plants. Miss Delf's work has led to the removal of the halophytes 

 from their former place among xerophytes. In this time-honored 

 category are still to be found the desert succulents and the desert 

 sclerophylls and microphylls. Enough is already known of the be- 

 havior of the last-named classes of plants to make it highly irrational 

 to class them together from any standpoint except that of a com- 



1 Kamerling, Z., Welche Pflanzen sollen wir Xorophyten nennen? Flora, 106: 

 433-454, 1914. 



2 Delf, E. Marion, The Meaning of Xerophily. Jour. Ecol., 3: 110-121, 1915. 



3 Bakke, A. L., Studies on the Transpiring Power of Plants as Indicated by 

 the Method of Standardized Hygrometric Paper. Jour. Ecol., 2: 145-173, 1914. 

 See review in this journal, 18: 222-224, August, 1915. 



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