19 



northwestern Connecticut, the leaves of which might key out 

 at Q. digitata, a southern species. If, however, the range of digi- 

 tata were indicated, its elimination would have been instant. 



For many trees, however, this difficulty will not present itself 

 and the book may be heartily recommended. Its size, about 

 five by six and one half inches, and its flexible cover make it a 

 convenient book to carry in the field. 



Ralph C. Benedict. 



Stevens' Diseases of Economic P. ants 



A new book entitled Diseases of Economic Plants, by F. L. 

 Stevens and J. G. Hall,* of the North Carolina Agricultural 

 Experiment Station, has recently appeared. This work is de- 

 signed to meet the needs of those students who wish to recognize, 

 wherever this can be done with any degree of certainty, and 

 treat diseases of plants without the laborious process of a detailed 

 microscopic study. Those characters are used in diagnosing 

 diseases which are evident to the naked eye or through the aid 

 of the hand lens, and technicalities are avoided so far as possible, 

 thus making the text a usable one to the agricultural students of 

 the lower grade. The work is confined mainly to the bacterial 

 and fungous diseases. 



The introductory chapters contain a brief historical sketch 

 of the development of the science of phytopathology; also statis- 

 tics regarding the damage caused by fungi, symptoms of disease, 

 methods of preventing diseases, formulae of the various fungicides 

 with directions as to the best methods of applying them, and a 

 discussion of the cost and profit resulting from their use. 



The body of the work is devoted to a description of the symp- 

 toms of the diseases of plants which are of economic importance 

 with directions as to the best methods of controlling them. 

 These diseases are classified according to the natural relationship 

 of the hosts on which they occur and all of the diseases of a given 

 host are treated under that host regardless of the relationships 

 of the fungi which cause the diseases. The terms used in desig- 



*Stevens, F. L., & Hall, J. G. Diseases of Economic Plants. Pp. i-ix + 1-513. 

 /. 1-214. The Macmillan Co., New York, 1910. Price $2.00. 



