RKVIEWS 753 



introduced into this country. A few trees of this species are now 

 grown in England. 



American foresters will be particularly interested in the contrast 

 drawn at considerable length between the Pacific coast and the Colo- 

 rado Douglas firs. The trees are contrasted in habit, summer shoot, 

 foliage, flowers, cones, wood, reproduction, resistance to frost, insect 

 attack, rate of growth, volume and yield of timber and silviculture. 



An important part of the paper is a detailed study of the micro- 

 scopical structure of the leaves of the several species and the study of 

 the oil distilled therefrom. Three plates of drawings and photographic 

 reproductions accompany the paper. 



Although the reviewer is not in sympathy with the present tendency 

 on the part of many taxonomists to split present well recognized, 

 widely distributed species into two or more he can see some merit in 

 considering the Pacific coast Douglas as specifically distinct from the 

 Colorado tree. He believes, however, that these two widely different 

 forms, as well as the variety cffisia, show all grades of intermediates. 

 He has observed these trees in the field in many different localities 

 and is convinced that thousands of trees exist which cannot be satis- 

 factorily relegated to one or the other of the two species of Douglas 

 recognized in this paper or to the variety. He is wondering if it is 

 not best to consider them all a single widely distributed species of 

 many forms. J. W. T. 



