BOOKS AND CURRENT LITERATURE 69 



This well executed and clear-cut investigation brings out strongly 

 the manner in which the vegetation of each community in a tension 

 region influences the environmental conditions and thereby promotes 

 invasion by plants of a more mesophytic character. Since our knowl- 

 edge of plant succession has been so widely extended and so thoroughly 

 elaborated, it promises important results that we should now divert our 

 attention from the successional relation which one community sustains 

 to another and turn our efforts to an investigation of the relation of 

 each successional stage to the physical conditions under which that 

 stage holds sway. — Fokrest Shreve. 



A New Biological Text. — This second edition of Professor Calkins 

 Biology, somewhat enlarged and revised, is a most welcome addition 

 to the existing list of elementary texts intended to present the general 

 facts of Biological phenomena, and differs from most of the books of 

 this class in that it focuses attention upon general principles and proc- 

 esses, rather than upon structures and types.^ 



The presentation of the subject matter is pleasing and orderl^^, 

 beginning with a consideration of living and lifeless matter, which is 

 well done in a brief space. The author then gives in order: the main 

 facts and activities of protoplasm and the cell organization and its 

 activities; organisms of one cell; organisms of tissues; plants the food 

 of animals, and the source of animal energy; organs and organ systems; 

 homology and the basis of classification; parasitism and physiological 

 adaptation; the perpetuation of adaptations. 



Throughout the text function occuj^ies a conspicuous position, 

 structures being considered only in relation to activities, and presented to 

 a less degree than is usual in texts intended for elementary instruction. 



The author, in a surprisingly brief space, has vividly protrayed the 

 essential processes of living things, and deserves the thanks, and sup- 

 port of those who must teach to beginners the basic facts of biology. — 

 William L. Tower. 



1 Calkins, Gary N. Biology. Pp. v + 255, illustrated. New York, Henry 

 Holt and Company, 1917. 





