March i6, 19 i6] 



NATURE 



55 



THE ELEMENTARY PRINCIPLES OF 

 CROP PRODUCTION. 

 \i, A Student's Book on Soils and Manures. By 

 Dr. E. J. Russell. Pp. ix -f 206. (Cambridge : 

 At the University Press, 1915.) Price ^s. 6d. 

 net. 

 {2) Soils and Plant Life as Related to Agriculture. 

 By Prof. J. C. Cunningham and W. H. Lance- 

 lot. Pp. XX + 348. (New York: The Macmillan 

 Co.; London: Macmillan and Co., Ltd., 1915.) 

 Price 55. net. 

 (i) T N the past the " Farm Institute " has been 

 X very inadequately represented in our 

 system of agricultural education, but of late much 

 has been done to remedy this defect, and, but for 

 the outbreak of war, more would by now have 

 been accomplished. This type of institution is 

 designed to serve primarily the needs of the 

 <:ountry youth whose general education is inade- 

 quate for the more advanced courses of the uni- 

 versities and agricultural colleges. The common 

 type of " farm institute " student will thus be the 

 iyouth whose previous education has been restricted 

 to the curriculum of the rural elementary school 

 with, in most cases, an intervening period of 

 practical work on the farm. 



It is for such students that the series of text- 

 books, of which Dr. Russell's volume is the latest 

 issue, is primarily intended, and by the standard of 

 their capabilities it must be judged. It is not clear 

 just in what way Dr. Russell intends his book to be 

 used. In scope and general mode of presentation 

 it may well serve as a pattern for the teacher, 

 but in the hands of the average " farm institute " 

 student we fear that, without considerable assist- 

 ance from the teacher, much of it will be rather 

 difficult reading. The fault lies probably not so 

 Tiuch with Dr. Russell, who has sacrificed nothing 

 in clearness and attractiveness of presentation, 

 ^s with the limitations of space imposed upon him, 

 which have necessitated a measure of condensa- 

 :ion which is undesirable in all elementary text- 

 books, and in none more so than in those provided 

 for the agricultural student. 



I For its refreshingly unorthodox and suggestive 

 treatment of a well-worn subject, the book is 

 iighly to be commended. An excellent feature is 

 ;he freedom with which the results of experiments 

 piade in this country have been drawn upon for 

 [he purposes of exposition. The Rothamsted ex- 

 JJeriments naturally have been chiefly drawn upon, 

 ')ut the useful work done elsewhere is more 

 idequately represented than in any other text- 

 >ook. The book is printed in attractive type, is 

 reely illustrated with photographs and diagrams, 

 NO. 2420, VOL. 97] 



and, apart from one or two obvious slips, leaves 

 nothing to be desired in precision. 



(2) In so far as they cover the same ground, 

 the treatment of the subject by Messrs. Cunning- 

 ham and Lancelot differs widely from that of Dr. 

 Russell. In their "first study in agriculture for 

 rural, grade, and high schools, based upon sound 

 educational principles," they adopt throughout the 

 didactic method which postulates at each stage 

 the approach to knowledge through individual 

 exjierimental inquiry. The student is led by easy 

 and connected stages through the study of the 

 origin, nature, and functions of the soil, to the 

 study of the outstanding phenomena of plant life, 

 and the application of the knowledge thus gained 

 to the practical problems of crop production. 



The numerous exercises in the first half of the 

 book are well designed and practical in their 

 bearing, and are described with a care which must 

 ensure success in the hands of the most inexpert 

 student. It is left to the student to draw his own 

 conclusions, although by leading questions his 

 attention is directed to the essential information 

 which it is desired that he shall acquire. 



The method of treatment is quite conventional, 

 but is so well and carefully worked out that the 

 intelligent student cannot fail to acquire a very 

 useful knowledge of the subject. A word of 

 commendation must be given to the photographic 

 illustrations, which are numerous and uniformly 

 good. 



The work is intended for the American student, 

 and the exercises and illustrations are largely 

 such as appeal most directly to him, but students 

 and teachers in this country will find much that 

 is useful and sug'gestive in it. 



OUR BOOKSHELF. 



Third Appendix to the Sixth Edition of Dana's 

 System of Mineralogy. By Prof. \V. E. Ford. 

 Completing the work to 1915. Pp. xiii + 87. 

 (New York : J. Wiley and Sons, Inc. ; London : 

 Chapman and Hall, Ltd., 1915.) Price 65. 6d. 

 net. 

 The study of mineralogy has received a new 

 stimulus in recent years from discoveries in radio- 

 activity and in the use of X-rays for the explora- 

 tion of crystal-structure. Just • as the determina- 

 i tion of optical principles from large and specially 

 i selected specimens laid the foundations of micro- 

 j scopic petrography, so these later physical experi- 

 I ments are bound to provide new methods of 

 j mineral analysis. A\'hile enlarging in the widest 

 I sense the bounds of human knowledge, they 

 i will reveal the alliances and differences among 

 minerals that bring a philosophic touch into the 

 i dry matter of classification. The third appendix 

 i to Dana's "System of Mineralogy," drawn up by 



