i86 



NA TURE 



[April 14, 1910 



instance, when on p. 7 we find that for a star- 

 connected motor the "total current" is V3 times the 

 current per phase, and on p. 8 we read that the 

 "total current" is \/3 times the "current per ter- 

 minal." What the authors may mean by their term 

 " total current " is not otherwise explained, and the 

 reader can only surmise that it is merely a conven- 

 tional way of introducing a current which is propor- 

 tional to the line current. The introduction of such 

 a conventional term is, however, quite unnecessary, 

 as is also the introduction of the term " apparent 

 efficiency " (p. 30), which has no physical meaning, 

 since it is the ratio of voltamperes, which is not 

 power, to watts, which is power. The authors also 

 distinguish between "real horse-power" and "brake 

 horse-power," and thus give the reader the idea that 

 brake-power is not real power, whereas they merely 

 mean to distinguish between the electrical power input 

 and the mechanical power output of a motor. This 

 is quite clear from the text, but why puzzle the reader 

 by using new or misapplying old terms? 



The efficiency tests described are all direct, that is 

 to say, input and output are measured and their ratio 

 calculated; the authors think this less inconvenient 

 than some method of determining efficiency by the 

 measurement of lost power, or, as they call it, the 

 " loading back " method. This may be true so long 

 as one has to deal with very small machines, but most 

 practical engineers prefer to test large machines by 

 some differential method. One counsel given by the 

 authors should be followed in testing every kind of 

 machine, namely, to plot results as the test proceeds, 

 so that doubtful observations may be eliminated before 

 the test is finished and the apparatus dismantled. The 

 tests described comprise a 50-horse-power induction 

 motor, a 500-kilowatt generator, a 300-kilowatt rotary 

 converter, a 75-horse-power single-phase railway 

 motor, a 450-kilowatt direct-current generator, a 40- 

 horse-power direct-current motor, and an enclosed 

 railway type of motor of only 12 horse-power. These 

 tests are explained very fully, and the results are 

 given in tables and curves, which are carefully com- 

 piled. The reader having once accustomed himself to 

 the authors' peculiar nomenclature (such as "rack" 

 for rheostat, and the terms alluded to in the first part 

 of this review) will find no difficulty in following the 

 sense of the text, and will derive some benefit from the 

 book by following the examples given if he has to 

 make similar tests. Gisbert Kapp. 



THE PHYSIOLOGICAL ANATOMY OF 

 PLANTS. 

 Physiologische Pflanzenanatomie. By Prof. G. 

 Haberlandt. Vierte neuarbeitete und vermehrte 

 Auflage. Pp. xviii+650. (Leipzig : W. Engelmann, 

 1909.) Price 19 marks. 



THE first edition of Prof. Haberlandt's well- 

 known work appeared in 1884, so that (as the 

 -author points out) it has already reached a respect- 

 able antiquity, as the age of scientific text-books is 

 reckoned. But, even before 1884, Haberlandt was 

 beginning to be known for researches of a kindred 

 ■sort, e.g. in the protective adaptations in seedlings 

 NO. 21 1 1, VOL. 83] 



(1877), and on the relation between structure and 

 function illustrated by the assimilatory tissues (1880). 

 By persistent work in this general direction he has 

 made himself the recognised authority on "physio- 

 logische Pflanzenanatomie." Haberlandt dedicated 

 his first edition "mit dem Ausdruck freundschaftlicher 

 Verehrung " to Prof. Schwendener.' This was appro- 

 priate, because it was Schwendener, in his cele- 

 brated work, "Das mechanische Prinzip, &c.," who 

 "raised anatomico-physiological research above the 

 level of casual tentative experiment, and marked it 

 out, once for all, as a definite department of science."^ 



Structure in relation to function is an old subject 

 of inquiry, but it was pursued on theological rather 

 than on scientific lines before the publication of the 

 " Origin of Species," and Hah^flandt's work is the 

 direct outcome of that book^ / At first, however, 

 adaptation was principally studied in the external 

 characters serving for fertilisation, dispersal of seeds, 

 &c. The meaning of histological peculiarities was 

 neglected, or strangely perverted, as, for instance, in 

 the comparatively recent dogmas that vessels do not 

 serve as water-pipes, or stomata for gaseous ex- 

 change. Schwendener 's work showed, in the most 

 -unexpected and brilliant way, the value to the plant 

 of such a neglected point as the sectional outline of 

 its mechanical tissues. After this the study of adapta- 

 tion could not be confined to obvious macroscopic 

 points, and Schwendener's work led up to the classi- 

 fication of tissues according to their physiological 

 character, which forms the basis of Haberlandt's 

 book. 



Since the first edition (1884), Haberlandt's book has 

 flourished and increased, as may be shown by the 

 simple process of counting the pages. Edition i. con- 

 tained 398 pp. ; edition iv. 650 pp. Edition i. had 

 139 figures in the text, and these have increased to 

 291. This represents the legitimate growth of the 

 subject, and it is to be noted that Haberlandt, from 

 the extent of his own work, is well fitted to make use 

 of the researches of others. Huxley has well said that 

 only a man who knows the raw material of science at 

 first hand can judge of the amount of " speculative 

 strain " that the elements of a given problem will 

 bear. It is this sort of knowledge that makes 

 Haberlandt an admirable critic and exponent of the 

 work of others. 



If we compare the present volume with the first 

 edition, the most striking point in which the modern 

 book diff^ers from its ancestor is the presence of a 

 chapter on sense-organs." Botanists will be glad to 

 have, in a compass of 50 pp. or so, a full discussion 

 of the scattered controversies on this subject. Haber- 

 landt's statolith theory of the sense-organs for 

 the perception of gravity, and of the lens-function of 

 the epidermis in relation to heliotropism, are the most 

 speculative of his views, and are by no means uni- 

 versally accepted, but the most sceptical can hardly 

 refuse to admire the skill with which these exciting- 

 hypotheses are upheld. F. D. 



1 The present dedication bears the additional words "on the completion 

 of his 80th birthday." 



2 Haberlandt's preface to his first edition, p. viii. 



