300 



NATURE 



[November 3, 192 1 



date work, within the reach of most, was greatly 

 needed, and with Mr. Iredale has undertaken to 

 supply the desideratum — hence this first volume 

 of the four which are to complete the work. 



In the neat and handy volume under notice the 

 authors deal with 188 species and their numerous 

 racial forms, comprised in the orders Casuarii, 

 Sphenisci, Procellariae, Freg-ati, Pelecani, Lari 

 (including the Limicolaj), Ralli (including the 

 Colymbidae and Podicipidse), Galli, and Columbae. 

 These orders and their component sub-orders, 

 families, and genera, together with their diagnostic 

 characters, are fully described. Under species the 

 necessary synonymy, plumages from nestling to 

 adult, nests and eggs, distribution and sub-species 

 — including the range and diagnostic definitions of 

 nearly 700 racial forms — are given. As a further 

 help to identification, a series of illustrations is fur- 

 nished in the form of ten coloured plates depicting 

 more especially hitherto unfigured species, imma- 

 ture birds, and nestlings in down ; while thirty- 

 six plates in monochrome contain some 300 figures 

 devoted to the elucidation of the characters upon 

 which the various species treated of in the volume 

 are based. These plates and drawings have been 

 prepared by Lilian Medland and are excellent, 

 but in some of the coloured plates the reproduc- 

 tions, though good and very useful, have not done 

 full justice to the artistic merits of the originals. 



We may not always be in sympathy with the 

 views of the authors on the vexed question of 

 nomenclature, and on the recognition of racial 

 forms which are sometimes based upon too trivial 

 characters ; nor are we aware that the curlew 

 sandpiper breeds in "Arctic Europe." These, 

 however, are small matters, and it is a pleasure 

 to recommend the book as one which, being 

 the product of consummate personal knowledge, 

 admirably fulfils its purpose, is excellent in all 

 respects, and will doubtless be much appreciated 

 by ornithologists. W. E, C. 



Climatic Factors in Agriculture. 



Agricultural Meteorology : The Effect of Weather 

 on Crops. By J. Warren Smith. (The Rural 

 Text-book Series.) Pp. xxiv + 304 + 8 plates. 

 (New York : The Macmillan Co. ; London : 

 Macmillan and Co., Ltd., 1920.) 135. net. 



IT has been said — and the statement is very 

 generally true^ — that in most soils the crop 

 yield is more affected by the weather than by 

 manuring and cultivation. For this reason it is 

 necessary to repeat most field trials for a number 

 of years in order that the variations due to climate 

 may be averaged out ; and if at the same time 

 meteorological records are taken it is possible to 

 NO. 2714, VOL. 108] 



trace out some of the relations between weather 

 fluctuations and the variations in yidd. The in- 

 finite variety in meteorological conditions and in 

 the factors concerned in plant growth makes statis- 

 tical examination of the results essential if trust- 

 worthy information is to be obtained. The great 

 value of long-continued experiments in this con- 

 nection is clearly pointed out in the book under 

 notice, and a large number of exceedingly inter- 

 esting correlations are given between the yields of 

 various crops and the weather characteristics — 

 rainfall and temperature — not only over the whole 

 year, but also over Hmited portions of the growing 

 season. As more data become available it will 

 be possible to specify the most critical periods of 

 plant growth, and the economic value of forecasts 

 of crop yields will be considerably increased. 



The effect of climate is not confined to the final 

 yield of the plant ; it operates throughout its whole 

 life, not only directly, but also indirectly through 

 the soil conditions, insect and other pests, and so 

 on. The relations must be considered, therefore, 

 from many aspects — ecological, physical, physio- 

 logical, to mention only a few. The difficulty of 

 presenting such diverse material in a continuous 

 and logical manner is obvious, and the author is to 

 be congratulated on the success he has achieved. 



Most readers of the work will be greatly in- 

 terested in the methods adopted by the U.S. 

 Weather Bureau in preparing and issuing weather 

 forecasts and warnings. Full advantage is taken 

 of these warnings, not only by the growers of 

 specialised crops, who employ various forms of 

 heaters to prevent damage from frost, but also by 

 the general farmer, especially in the important 

 harvesting periods. 



In one or two minor aspects the book might be 

 improved. The explanation of ' the method of 

 working out correlation coefficients could be 

 shortened; the student should be expected to 

 know the way to solve simultaneous equations. 

 Further, the section on physiological indices 

 should adequately include the work of F. F. 

 Blackman and V. H. Blackman, and a discussion 

 of the views of Matisse would not be out of place. 



The suggested laboratory exercises at the end 

 of each chapter are excellent. They are intended 

 primarily for university students, but many of 

 them contain stimulating suggestions which could 

 profitably be followed up by experienced research 

 workers. 



Agricultural meteorology must inevitably attract 

 more workers in the future. It is to be hoped 

 that the literature of the subject will maintain the 

 high standard set up in this book. 



B. A. Keen. 



