November 5, 1891] 



NATURE 



science, and it is sure to be no less popular among olJer 

 people who appreciate a sound and easy guide to the 

 mysteries of practical electricity. 



In taking leave of this work, we have only to say, what 

 has already been indicated above, that an extension of 

 the editorial remarks, and their absorption into the general 

 current of the text, with consequent re-writing of some 

 of the chapters, would render it more homogeneous, and 

 throughout more in accordance with the electrical spirit 

 of the age. Still, the clearness of its arrangement and 

 style more than compensate for the disadvantages 

 necessarily attending an edited English edition of a 

 foreign scientific treatise, however popular. As a whole, 

 it reflects credit on all concerned — translators, editor, 

 and publishers alike. Its publication may even do some- 

 thing towards arousing an interest in electricity in circles, 

 even in this proverbially practical country, where the 

 light of science can hardly be said to have yet penetrated. 



A. Gray. 



BIOLOGY OF SEASIDE PLANTS. 

 Die indo-malayiscke Strandjiora. Von A. F. W. 



Schimper. Mit 7 Textfiguren, einer Karte, und 7 



Tafeln. (Jena : Gustav Fischer, 1891.) 

 Ueber die Mangrove-Vegetation im malayischen Archi- 



pel. Von G. Karsten. Bibliotheca Botanica, Heft 22. 



(Cassel : Theodor Fischer, 1891.) 



THESE two essays are exceedingly interesting con- 

 tributions to our knowledge of plant life on tropical 

 sea-shores. They partly cover the same ground, partly 

 supplement each other, and to some extent review and 

 summarize the work of previous observers. Schimper 

 treats of the salt-loving plants of the sea-shore generally, 

 whilst Karsten's investigations are limited to the purely 

 mangrove vegetation. Karsten also enters more fully 

 into the formation of seeds — that is to say, into the de- 

 velopment of the embryo-sac, the endosperm, and the 

 embryo ; and he follows up their germination and 

 subsequent growth. 



But the object of this notice is to give some general 

 idea of the subject rather than a critical exposition of the 

 writings of the authors named, for they are the first at- 

 tempts at a connected description of the vegetation of 

 tropical sea-shores. 



The mangrove 1 vegetation— that is, the vegetation of the 

 tidal forests— exhibits comparatively little variety, though 

 the components belong to several different natural orders. 

 First come the Rhizophoreae— genera Rhizophora (both 

 in the Old World and in America), Bruguiera, Ceriops, 

 and Kandelia ; Combretaceae— Lumnitzera (Laguncularia 

 in America); Lythraceas— Sonneratia ; Meliaceae— Carapa 



The word mangrove looks quite English, but it .ippears to be a corruption 

 or modification q{ mangro or tnungto, the name commonly applied, accord- 

 ing to RumpF (1750), and Blume {Museuin liotaniciiin, i. p. 132), in Dutch 

 Guiana to Rhizophora Mangle. Hjwever, it was employed in its present 

 form by Dampier, Sbane, and oth-r writers of the seventeenth century, and 

 it is now applied to a number of different trees and shrubs that onscitute 

 the outermost fringe of vegetation on tropical coastf. It is also used to 

 designate these shrub; and trees c jllectively. Mangi-imngi is the generic 

 term in the Malay Islands for these trees and shrubs, and the different kinds 

 arc distinguished by alTixes. In Brazil, Rhizophora Mangle is called mangle 

 and ntangm ; and in P.inams, on the authority of Sjemxnn ('• Die Volks- 

 ntinen der amerikanischen Pflanzin"), the former name is ciirren*, with 

 various qualifying affixes. In Grisebach's list of col >nial names of plants 

 (' F'"""* of the British West Indian Islands," p. 785). we finl ma:jgrovi 

 \Rhizopliora mangle) ; black m ingrove {Avicennia nitida) ; white mmgrove 

 (/- iguncularia racemosa) \ and Zaragoza mangr>vi (Conocarpiis erictiis). 



NO. I 149, VOL. 45] 



{Carapa guianensis, a native of tropical America and 

 west tropical Africa, does not appear to inhabit the tidal 

 forests); Myrsineas- ^giceras; Rubiaceae- Scyphiphora; 

 Verbenaceae— Avicennia (both in the Old World and in 

 America) ; Acanthaceae — Acanthus ilicifolius ; Palmae— 

 Nipa fruticans. 



The foregoing are the principal and widely-spread 

 trees and shrubs of the mangrove girdle of muddy 

 tropical shores ; but this list might be largely augmented 

 if we included those forming the tidal forests of the Bay 

 of Bengal, and similar situations. Thus, in the Sunder- 

 bun, as Mr. C. B. Clarke informs me, the Sundra tree 

 {Heritiera Pomes) abounds to such an extent that a rail- 

 way is almost entirely devoted to carrying the wood to 

 Calcutta, of which city it is the fire-wood. Among other 

 common trees and shrubs are Hibiscus tiliaceus, Sapin- 

 dus Daniira, Dalbergia inonosperma, Derris uliginosa, 

 Oxystelma esculentum, Dolichandrone Rheedei, Prctnna 

 integrifolia, Clerodendron inerine, Pandani, Phoenix 

 paludosa, and Cocos micifera. Mr. Clarke further informs 

 me that the milk of the coco-nut in the Sunderbun is 

 so salt as to be undrinkable. This is a very remarkable 

 fact, and scarcely in harmony with the observations of 

 Schimper, Karsten, and others, so far as mangrove plants 

 are concerned generally. 



In this connection it may be mentioned that mangrove 

 plarits have mostly very thick leaves, with few, very 

 deeply seated stomata, so that transpiration is reduced 

 to as low a minimum as in true xerophytes. As it is 

 obvious that transpiration is not checked in halophytes 

 because of a lack of water, it must be accounted for in 

 some other way ; and, as it has been found that the 

 accumulation of salt in the tissues of the leaves beyond a 

 certain quantity, varying in different plants, prevents the 

 formation of starch and glucose, it is assumed that it is 

 of a protective character ; that, in short, smallness of 

 transpiration means smallness of absorption, and thus 

 no more salt is taken into the tissues of the plant than it 

 is capable of assimilating. The correctness of this view 

 is strongly supported by the fact that mangroves, grown 

 in soil free, or practically free, from chloride of sodium, 

 develop foliage of less substance, furnished with a 

 larger number of stomata. 



Turning to another phase in the life-history of man- 

 groves — namely, reproduction — we find special provisions, 

 suitable to the exceptional conditions, to insure the pro- 

 pagation of the species. Most of the members of the 

 Rhizophorete, for instance, are, in a sense, viviparous — 

 that is to say, the seed germinates on the parent plant. 

 Only one ovule is developed, the rest being aborted ; 

 and when the seed is ripe, the radicle, or primary root, 

 grows through the apex of the fruit, assuming a slender 

 club-shaped form, with the centre of gravity nearest the 

 organic base, so that, when it eventually separates from 

 the parent, it falls in such a manner that the radicle 

 penetrates the mud, and usually sufficiently to withstand 

 the ebb and flow of the water. The size and length of 

 the viviparous radicle varies considerably in different 

 genera, and even in different species, of the same genus, 

 attaining its greatest development in Rhizophora mticro- 

 nata, the forepost of the Asiatic mangroves, and perhaps 

 the only one that sometimes grows where the soil is 

 always submerged. In this the viviparous radicle is 



