March 17, 1921] 



NATURE 



69 



ception when treating the questions that really 

 move the meteorological world, but it is not so 

 helpful as the bolder course. What we should 

 like to know is almost as important to a subject 

 as what we do know beyond dispute. 



It is only when we reach part iv. — "Factors of 

 Climatic Control " — that the author becomes 

 really argumentative, and thereby most interest- 

 ing, in suggesting and endeavouring to demon- 

 strate that dust projected into the stratosphere 

 by volcanoes is the efficient cause of prolonged 

 changes of temperature that express themselves 

 in climatic changes, after examining and rejecting 

 all the other explanations which have been pro- 

 posed. On reaching those chapters we feel once 

 more in the fresh, free air, and the solicitude for 

 the academic robe is disregarded. The oppres- 

 sion of the four walls of the laboratory vanishes. 

 There is a sense of relief when the author boldly 

 calculates the rates of fall of dust under Stokes's 

 law without taking account of the counteracting 

 influence of eddy motion which is so potent 

 throughout the atmosphere in keeping solid and 

 liquid particles in suspension. It would tax our 

 space too much to consider why the stratosphere 

 in particular should have to carry this additional 

 burden, but the whole subject is full of interest, 

 and now that he has taken off the academic gloves 

 and faced so controversial a question as the cause 

 of the Ice-age we look to Prof. Humphreys to 

 let us have his views about various problems of 

 the circulation of the atmosphere in general, and 

 of cyclonic circulations in particular, to which 

 in the past the meteorologists of the United 

 States have made some notable contributions 

 which might now be reviewed and perhaps re- 

 vised. Meanwhile he deserves our hearty thanks 

 for a very useful and handy book of reference 

 indispensable for the meteorological library. 



Napier Shaw. 



New American Text-books of Botany. 



(i) General Botany for Universities and Colleges. 



By Prof. Hiram D. Densmore. Pp. xii + 459. 



(Boston and London: Ginn and Co., 1920.) 



125. 6d. net. 

 (2) Laboratory and Field Exercises for "General 



Botany/' By Prof. Hiram D. Densmore. 



Pp. viii+199. (Boston and London: Ginn and 



Co., 1920.) 35. gd. net. 



(i) pROF. DENSMORE'S avowed intention is 

 X to "furnish both student and instructor 

 with a helpful and connected statement of the more 

 important facts and principles of modern botany." 

 It is but rarely that an elementary text-book meets 

 NO. 2681, VOL. 107] 



the requirements of teacher and student in equal 

 degree ; in striving after this ideal, Prof. Densmore 

 has, one fears, fallen between two stools. For 

 the student the statement is not sufficiently con- 

 nected, and the teacher of university grade should 

 not require help in regard to such elementary 

 matter as fills the bulk of this book. 



The discontinuous character of the text is ag- 

 gravated by a noticeable lack of balance. Thus 

 while the structure of stems, leaves, and roots 

 is disposed of in thirty-three pages, an equal 

 amount of space is devoted to an account of plant- 

 breeding and evolution, which, moreover, deals 

 principally with such modern developments as 

 Mendelism and the mutation theory, touching but 

 lightly on the more general aspects of evolution. 

 The discussion of floral construction is inadequate, 

 and the same remark applies to the chapter on 

 fungi, which, in addition, is badly arranged, and 

 gives no clue to the phylogeny of that group, the 

 " simple classification " on p. 243 being in reality 

 no classification at all. The author's didactic 

 methods are often peculiar. Growth-movements 

 are fully discussed before any account has been 

 given of growth itself. The complex woody 

 stem is described before the simpler herbaceous 

 type. Part iii. ("Representative Families and 

 Species of the Spring Flora") would fit better 

 into a book of Nature-study than it does into the 

 present volume, where its usefulness is not ap- 

 parent. It is only fair to note that some of the 

 foregoing criticisms are repelled in advance in the 

 author's preface, where he professes his adherence 

 to a "biological, economic, and ecological point 

 of view " in preference to a taxonomic or phylo- 

 genetic outlook. 



Opinions differ widely as to the best form of 

 elementary botanical course, but most teachers 

 will agree that it is better to concentrate even 

 unduly on one aspect of the science — say, phylo- 

 geny, physiology, or even taxonomy — than to 

 adopt the kaleidoscopic method favoured by Prof. 

 Densmore, whose hint as to the lack of interest 

 shown by beginning students in most aspects of 

 botany (the fortunate exception being "cellular 

 biology ") is significant. It is claimed that the 

 sections dealing with structure follow the teach- 

 ings of the "newer anatomy "; in the absence of 

 a precise definition, one is left in doubt as to how 

 far this claim is justified, but the reviewer has 

 searched in vain for any important anatomical 

 facts or theories which have not figured in our 

 elementary text-books for many years past. No 

 mention whatever is made of palaeobotanical evi- 

 dence, which one would naturally expect to have 

 an important bearing on the "newer anatomy." 



There are a number of obvious inaccuracies 



