Nov. 25, 1875J 



NATURE 



65 



ceptibly. From the law of continuity this must neces- 

 sarily be the case in the transition of every solid into a 

 gas, yet we are not aware of any definite experiments on 

 this point. 



The reciprocity of radiation and absorption is well 



litrated by a comparison of the fluorescent and absorp- 

 1 spectrum of what the translator terms napthalin red ; 

 presume rosaniline is meant. If the solar spectrum 

 projected upon a glass cell containing this liquid, the 



orescence exhibited in Fig. 6 (2) is seen. In the upper 

 gram is shown the absorption spectrum obtained by 

 u ansmitting the solar spectrum through the same solution, 

 and it will be clearer to the eye than it is in the diagram, 

 that the three regions of strong fluorescence are in the 

 same position as the three principal absorption bands. 

 By employing a solution of proper strength, it will be 

 found indeed that " every dark band in the absorption 

 spectrum corresponds to a bright band in the fluorescing 

 spectrum." (p. 190.) 



The last diagram we give shows in an instructive 

 manner the irrationality of the dispersion spectrum, by 

 a comparison of the normal spectrum yielded by a diffrac- 

 tion grating with the ordinary prismatic spectrum (Fig. 7, 

 i). The last sentence in chap. 19, referring to this 

 diagram, is badly translated, and certainly ought to be 

 amended, for as it stands at present it is unintelligible. 



We have said enough to show that Prof. Lommel's 

 treatise is a useful contribution to the International Serie?, 

 and is a book that can thoroughly be understood and 

 enjoyed by any intelligent reader who may not have had 

 any special scientific training. The familiar chromo- 

 lithograph of different spectra which adorns the title-page 

 of the volume has by this time lost its novelty and 

 become wearisome. No book on chemistry, astronomy 

 or physics seems to be issued without it. Though the 

 spectroscope is a wonderful and powerful instrument, yet 

 the prominence of this subject is a little apt to throw 

 equally valuable instruments into the background. 



W. F. B. 



DARWIN ON CLIMBING PLANTS 

 The Movements and Habits of Climbing Plants. By 



Chas. Darwin, M.A., F.R.S., &c. Second Edition, 



revised. With Illustrations. (London : J. Murray, 



1875.) 



' I "HIS volume is a reprint of Mr. Darwin's well-known 



J- treatise on the habits of climbing plants, published 



in 1865 in the ninth volume of the "Journal of the 



^-'nnean Society," with such additions and corrections as 



e progress of knowledge since that time has rendered 

 necessary. Although the subject had been investigated 

 previously to that time by the German physiologists 

 Palm and Von Mohl, it was Mr. Darwin's publication, 

 describing many facts not previously recorded, that first 

 introduced the remarkable phenomena connected with it 

 to the notice of the general public. The phrase Climbing 

 Plant is used by Mr. Darwin as a generic term for all 

 those which, provided themselves with but weak stems 

 that have no power of standing erect, avail them- 

 selves of the assistance of neighbouring plants for the 

 purpose of raising their foliage and flowers to a consider- 

 able height from the ground. The plants included under 



this head are arranged in four divisions, according to the 

 part that is modified in order to subserve this purpose : 

 (i) Twining Plants (called in the first edition Spiral 

 Twiners), in which the stem is the climbing organ ; (2) 

 Leaf-climbers, which climb by the aid of the petiole or 

 some other portion of the leaf ; (3) Tendril-bearers, by 

 far the most numerous class, which are provided with 

 tendrils specially contrived for this purpose ; and (4) 

 Hook and root-climbers, which chmb by the aid of hooks 

 on aerial roots, or merely scramble over other plants. In 

 all these classes except the last, the mechanical means 

 by which the climbing is effected is a sensitiveness and 

 power of revolution possessed by the extremity of the 

 stem or tendril, or by the petiole. 



The origin of this peculiar power is one of the most 

 interesting points of the inquiry. In some cases, as Passi- 

 floracese and Cucurbitaceas, it is possessed by nearly or 

 quite every species of the order ; other orders, as Legu- 

 minosas, include species belonging to two or three divisions 

 of climbers, along with a large number which do not pos- 

 sess the power ; while in others, as Compositae, Rubiacea?, 

 Scrophulariacese, and Liliaceae, it belongs to only a very 

 few out of a large number of genera. From these facts, 

 and the wide separation, on any system of natural classi- 

 fication, of the orders which contain climbing plants, Mr. 

 Darwin draws the conclusion that "the capacity of 

 revolving, on which most climbers depend, is inherent, 

 though undeveloped, in almost every plant in the vegetable 

 kingdom" — a conclusion which seems to us strongly con- 

 firmed by the fact that sensitiveness and a slight power 

 of spontaneous motion are possessed by some parts of 

 flowers where it is of no use for climbing purposes, as the 

 flower-stalks of Maiiratidia and Brassica Napus ; and by 

 the remarkable observation of Fritz Miiller — one of the 

 most interesting additional notes in the present volume — 

 that " the stems, whilst young, of an Alisma and of a 

 Linian" which do not climb, " are continually performing 

 slight movements to all points of the compass, like those 

 of climbing plants.'' 



These observations lead Mr. Darwin to a discussion of 

 the nature of the difference between the so-called " spon- 

 taneous" power of motion of some plants and that pos- 

 sessed by animals, which he sums up as follows : — 



"It has often been vaguely asserted that plants are 

 distinguished from animals by not having the power of 

 movement. It should rather be said that plants acquire 

 and display this power only when it is of some advantage 

 to them ; this being of comparatively rare occurrence, as 

 they are affixed to the ground, and food is brought to 

 them by the air and rain." 



In the present work Mr. Darwin makes'ample reference 

 to the light that has been thrown on the habits and move- 

 ments of climbing plants by researches of a later date 

 than the publication of the first edition, especially those 

 carried out in the Wiirzburg Laboratory by De Vries and 

 Sachs ; and one of the most important of the additions 

 is a paragraph wherein he expresses his partial dissent on 

 one point from the conclusions of the last-named high 

 authority. In his "Text-book of Botany," Sachs attri- 

 butes all the movements of tendrils to rapid growth 

 on the side opposite to that which becomes concave ; 

 these movements consisting of revolving nutation, the 

 bending to and from the light and in opposition to gravity, 

 those caused by touch, and spiral contraction. While 



