220 THE PLANT WORLD 



related Variability. Y. Some Applications of Statistical Biological 

 Study. 



The remainder of the book is devoted to tables and formulae used 

 iu the calculation of curves. These are conveniently arranged, and are 

 indispensable in the line of biological work. 



This little volume will i^rove very useful to all who wish to make 

 an exact quantitative study of the variation of organisms, which study 

 we believe is destined to receive great attention in the future, and to 

 give us an exact basis for testing many of the current theories and 

 speculations regarding the various factors of organic evolution. — C. L. S 



Manual of the Floka of the Northern States and Canada. By Na- 

 thaniel Lord Britton, Ph. D. 12mo., pp. X, 1080. New York, 

 Henry Holt and Company. Price $2.25. 



It is a neat-appearing and comi^act little volume which Dr. Britton 

 has given us as a competitor to Gray's classic work, and one which 

 arouses interest not merely in the treatment of species by the author, 

 but in the arrangement and mechanical construction of the book. 



Brevity requires, in a comprehensive manual of this kind, the abso- 

 lute suppression of unnecessary matter; so that while many persons 

 will feel annoyance at the omission of most of the synonyms, the aver- 

 age student will accustom himself to using the book for the sake of the 

 descriptions, and will look elsewhere for his bibliography. The clear- 

 ness and comparative fulness of the diagnoses of species, as well as the 

 excellence of all the keys, cannot fail to find high favor among amateur 

 workers. One of the very best features, in contrast with Dr. Gray's 

 Manual, is the collation of all the divisions of a key rather than a pro- 

 miscuous distribution through the pages of the text. We are pleased 

 to observe, also, the insertion of ordinal names and their descriptions. 



In the preparation of his text the author has freely availed himself 

 of the cooperation of specialists, and the treatment of many families 

 has been revised or contributed outright by Dr. Small and Dr. Rydberg. 

 There is a tendency to radicalism in contrast to Britton and Brown's 

 Illustrated Flora, which was somewhat conservative. Several hundred 

 additional species are included, many of them new, but we regret the 

 lack of uniformity in designating these new species, as also the careless 

 proof-reading which has resulted in such errors as "Gymnandeniopsis," 

 a genus said to be derived from "Gymnandenia." 



As a thoroughlj^ modern and practical presentation of our present 

 knowledge of the northeastern flora, based on the most approved prin- 

 ciples of nomenclature and classification, this book will take its place 

 as our standard manual. — C. L. P. 



