312 BOTANICAL GAZETTE [OCTOBER 
importance of agricultural plants and their future possibilities. It will be 
found a valuable reference book upon many questions pertaining to economic 
and commercial aspects of tropical plants. Botanically, however, the book 
is often defective, as for example, in speaking of the growth of Cannabis sativa 
for its opium-like drug, the author says: “The male flowers are removed in 
November, for if the female flowers are fertilized there is no formation of the 
drug.” —O. W. CALDWELL. 
The geography of ferns 
It is a praiseworthy thing for an investigator, who has devoted years to 
taxonomic exploration, to bring together in readable form the many things of 
geographic interest which he has observed. It is exactly this service which 
Curis, the well-known student of the ferns, has now performed. The volume 
is divided into two parts, corresponding somewhat to the usual divisions of 
ecological and floristic geography. Curist regards the ferns as controlled 
y the same general distributional factors as the seed plants, the most note- 
worthy difference consisting in the pronounced tendency of ferns to be hygro- 
phytic mesotherms. The great fern areas of the world are essentially coin- 
cident with the forest areas, very few species existing where the rainfall is less 
than 60 cm., and the greatest development occurring where the rainfall is over 
The edaphic conditions under which ferns live are first noted, attention 
being called to the fact that most species are humus forms, and but slightly 
dependent on the mineral nature of the soil. Under the head of climatic 
conditions, a number of characteristic fern formations are described. T e 
hygrophytic ferns are treated at considerable length, especial attention being 
devoted to the epiphytic forms. The features of the xerophytic ferns are well 
portrayed. In the floristic part of the work, consideration is given to a number 
of cosmopolites, and also to endemic forms and to species with disconnected 
areas. The body of the second part is made up of the treatment of the floristic 
regions of the world. Here, as elsewhere in the volume, the author makes it very 
clear that the ferns, in spite of their great age, are far from being a senescent 
up. 
The volume is a mine of information, and will be of the highest value to 
all botanists. The excellent index makes it possible to find at once the known 
ecological and geographic facts concerning most living ferns —HENRY C. 
CowLEs. 
An organic chemistry : 
The third English edition of HoLteman’s. Organic chemistry has just 
appeared,* edited by A. JAMIESON WALKER. The value of the book as 2 text 
3 Curist, H., Die Geographie der Farne. 8vo. pp. 358, with frontispiece, Sigs. 
129 (mostly photographic reproductions), and 3 maps. Jena: Gustav Fischer. 19° 
+Hottemay, A. F., A textbook of organic chemistry. 8vo. pp. x*+599- #85 
80. New York: John Wiley & Sons. 1910. 
