Book Reviews for January 



The Germ Cycle in Animals. Robert W. Hagner. Pp. x+346. 

 The MacMillan Co. $1.75. 



Ever since Weismann so forcibly championed the theory of the 

 continuity of the germ plasm and pointed out how his theory under- 

 mined the basis of such theories regarding the method of evolution 

 as those of Darwin and Lamarck, biologists have been keen for any 

 presentation of new facts, regarding the germ plasm or discussion 

 of the data already known. This book of Hagner's is largely a 

 systematic presentation of the data now in hand regarding early 

 differentiation and the life cycle of the germ cells. The intro- 

 ductory chapters, one and two, are a brief resume of the cell theory 

 especially as it applies to the germ cells. Chapter 3 is on the germ 

 cell cycle in the fly, Miastor, in which the germ cells are differen- 

 tiated very early and are easily recognized throughout the life 

 history. Chapters 4 to 7 inclusive collect the facts regarding 

 early differentiation and the continued recognition of the germ cells 

 in the several animal subkingdoms. Chapters 8 and 9 discuss the 

 significance of various constituents recognizable in the germ cells. 

 Chapter 10 is on the germ plasm theory. There then follow some 

 twenty-six pages of bibliography. 



The book is one that will be welcome by all students of biology 

 and by those general readers who wish to keep up to date on biologi- 

 cal fact and theory. The book is clearly written, so that even one 

 who is not an expert in cell studies may understand readily the 

 progress that is being made. 



Elements of Forestry. F. F. Moon and N. C. Brown. Pp. xvii 

 + 392. John Wiley & Sons. $2.00. 



This is an exceedingly good book on forestry — the best that has 

 yet come to the attention of the reviewer. In the opening chapter 

 the authors show the relation between forestry and tree culture and 

 its importance to lumbering. Contrast is made between forestry 

 conditions in this country and those in Europe. The remainder 

 of Part I, consisting of fourteen chapters, is devoted to the various 

 phases of forestry, study of the tree, systems of management, 

 rejuvenation, forestry mensuration, lumbering, wood utilization 

 and preservation, the finance of the forest. Part II, of eight addi- 

 tional chapters and appendix, describes the various forest regions 



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