!3 



merit is by countries alphabetically. The entries under each 

 country are, as far as practicable, in the language of the country. 

 At the beginning an index gives page reference to each country. 

 At the end there is an index with a page reference to each per- 

 sonal entry. 

 The entries under each country include: 



(a) Societies with their postal addresses. 



(b) Institutions wholly or chiefly botanical, their addresses 

 and departments; educational institutions having separate de- 

 partments dealing with botanical teaching and research. 



(c) The surname and initials of Botanists, both professional 

 and amateur, with information as to their offices and profes- 

 sional qualifications, their postal addresses, and their special 

 botanical interests." 



In the index to countries some 130 countries are listed, in 

 some there is only one name mentioned, lonely places for bot- 

 anists, as in Angola, Liberia, and Zanzibar. The list of insti- 

 tutions and botanists in the United States requires 148 pages. 

 Probably the list of amateur botanists is more complete for the 

 United States than for many other countries. Some 22,000 

 names of individuals are listed in the book. 



George T. Hastings 



Types of Humus Layer in the Forests of Northeastern 

 United States. By L. G. Romell and S. O. Heiberg. Ecology 

 /,?:567-608, 1931. 



The paper represents a first systematic effort of applying 

 outside Europe the principles and method laid down by P. E. 

 M tiller in his classical studies on natural types of humus layer. 

 It is also a contribution to the question of classification and 

 nomenclature of forest humus layers in general. After a critical 

 review of the different proposals of classification, the authors 

 conclude that Miiller's system fits the natural conditions best. 

 That this holds true for American conditions is indicated espe- 

 cially by the flora characteristic of different types of humus 

 layer. A fundamental point of Mtillers system is that the classi- 

 fication applies to the entire humus layer (i.e., the top layer of 

 soil, owing its characteristic features largely to its humus con- 

 tent; no matter whether this content is high or low and whether 

 the humus is "incorporated" or not). The authors strongly op- 



