June 6, 1872] 



NATURE 



III 



A' 



MR. BENTHAM'S ANNIVERSARY ADDRESS 



TO THE LINNEAN SOCIETY* 



S a general summary of the current zoological literature the 

 ' Zoolog'cal Record" maintains its high value. The 

 volume for 1S70 has lately appeared under the new editorship of 

 Mr. Newton, and the arrangements now m.ide for its further 

 prosecution are very hopeful ; yet I must again urge upon all our 

 Fellows, who, as amateur zoologists or patrons of the science, 

 have joined our ranks, to give their further support to the "Zoo- 

 logical Record " .Vssociation in order to secure the continuance 

 of this annual summary for the sake of the working members, to 

 whom it is so essential. I would also call attention to the sketch 

 of the ornithological works recently published or in progress 

 contained in Ihe last number of the Ibis, an example which it 

 were to be wished were regularly followed in all periodicals 

 specially de»oted to any branch of our sciences. The Reports 

 on the contributions lo the various branches of zoology inserted 

 in Wiegmann's " Archiv" under the editorship of, and some of 

 them compiled by, Troschel, replace in some measure the 

 " Zoological Record " for the German public, and are kept up 

 nearly to the same period, some of the reports for 1870 hiving 

 already appeared ; they are also much to be commended, al- 

 though they may not have quite the method and completeness 

 of the "Zoological Record." I have further to congratulate 

 science in general on the near completion of the Royal Society's 

 great Catalogue of Scientific Papers, the sixth and last volume 

 of which is far advanced, and likely to be in our hands by the 

 commencement of the next session of the Society. 



In Botany, Piitzel's excellent aud much-improved second 

 edition of his " Thesaurus " is rapidly going through the press, 

 and brings the repertory of separate botanical works down to 

 the year 1871. Ciirrent botanical publications are also generally 

 noticed in various botanical publications, especially the "Gior- 

 nale Botanico Italiano," edited by Prof. Caruel ; the " Flora " of 

 Ratisbon ; the "Botanische Zeitung," continued since the 

 death of v. Mohl by A. de Bary ; the " Bulletin de la Socicte 

 Botanique de France," which comprises perhaps the fullest 

 bibliographical review ; and the Joiiriml of Botany, which 

 promises well under the new and active editorship of Dr. Trimen. 

 But, with the exception of lichenography, the bibliography of 

 which is brought down to the year 1870 in Kreppelhuber's 

 detailed " Ili^toiy and Literature of Lichenology, " we have no 

 comprehensive references to Memoirs and Papers published 

 since 1863, the term of the Royal Society's Catalogue, and 

 we feel much the want of an annual summary corresponding to 

 the " Zoological Record." 



A woik has recently appeared which has naturally attracted 

 much of my attention as being intimately connected with a branch 

 of the science which I have on several occasions taken as the 

 subject of my annual Addresses, and as being the result of long 

 and careful simly of the great and varied mass of data col- 

 lected by its laborious and distinguished author. I speak of 

 Grisebach's " Vegetation of the Earth according to its climato- 

 logical distribution. " The general scope and plan of the work has 

 been recently noticed in an article in Nature,! and I shall on 

 the present occasion confine myself to a few obsei-vations on his 

 views with reference to some of those regions or districts to 

 which I had intended to call your attention in my last year's 

 Address. 



One of the most interesting of these regions is the Japanese, 

 or the greater part of Grisebach's Chino-Japanese regions, that 

 is, the Japanese islands and opposite coasts of the Asiatic conti- 

 nent. The peculiarities of its flora have been accounted for, 

 up in considerations depending chiefly on origin, in a well-known 

 paper by Asa Gray (Mem. Amer. Acad, new ser. voh vi. p. 424), 

 whose views are fully coincided in by Maximowicz and others, 

 but strongly objec'.ed to formerly by jiliquel and now by Grise- 

 bach, who relies upon climatological and other physical con- 

 siderations. It appears to me that this is a strong instance of 

 the combined effects of the two agents as explained in my above- 

 mentioned Address of 1869 (p. 15 ; Proc. Linn. Soc. 186S-69, p. 

 Ixxvii. ) The main features of this flora are the mutual inter- 

 grafting of northern and tropical types, and the number of highly 

 differeniated mlemic or widely dissevered monotypic or almost 

 monotypic races ; the former due to physical, the latter to de- 

 rivative cruses. 

 ^With regard to the endemic or widely dissevered highly differ- 



* Delivered Friday, May 24, and abridged. 

 • t No. 123, April 11, 1872. 



entiated races (monotypic genera, sections, or very distinct ' 

 species), Grisebach's views differ widely from those of Asa Gray 

 and other modern naturalists who adopt more or less the theory 

 of evolution. Grisebach, as already observed, entirely ignores 

 community of origin of closely allied or representative species, 

 and is but little disposed to take into consideration ancient dis- 

 persion uniler geological conditions different from the present 

 ones. Each species he believes has arisen — he had formerly 

 Slid been created, an expression he now abandons in order not 

 to be supposed to prejudge a question which admits of no posi- 

 tive solution — each species has arisen in a particular spot (from 

 what materials he thinks it vain to inquire), under the influence 

 of physical and other external conditions, and has spread more 

 or less in every direction from this birthplace or centre as far as 

 those external conditions have prevailed, and in so far as their 

 progress has been unopposed by insurmountable physical or 

 climatological barriers. In conformity with these views he ex- 

 plains clo.-ely allied and representative species in a passage which 

 I give at length for fear of misrepresenting him by an abstract. 

 " The birthplace [Eutstclningsort) oi a plant species," he says, 

 vol. i. p. 515, "may be taken as the most perfect expression of 

 the concordance between the physical life-conditions of the 

 place and th.e organisation of the phnt ; for this suitability 

 to given Influences of inorgrnic nature gives the highest measure 

 of the capability of preservatioi which life strives to attain. 

 Upon these propositions is founded the conclusion, that the 

 nearer the centres of different plants are placed geographically, 

 and the less different are therefore their climatological condi- 

 tions, the more similar must be their organisation, or, what 

 amounts to the same thing, the more species will have arisen in 

 the same genus. This phenomenon is exhibited in all places where 

 we can compare endemic species whose dispersion is limited, 

 but in islands which have a peculiar vegetation it is less pro- 

 nounced than in continents. From any one point climate is 

 gradually altered, like the radii of a circle which gradually diverge 

 more and more from each other from the centre to the circum- 

 ference. In a continent the whole area of the circle may be sup- 

 posed to be suited to the production of changes in organisation ; 

 in an archipelago it is interrupted by the sea, and here, therefore, 

 few similar species have arisen. Another consideration to be 

 taken into account is that genera when compared with each 

 other are unequally susceptible of change (vcrandeniiv^sjahig); 

 their species, therefore, to keep to the same metaphor, will be 

 found arranged at greater or less distances from each other in the 

 radii of the circle. If the area of the continuous land is small, 

 monotypes will have more readily arisen — genera which, on the 

 one hand, are very little or not at all susceptible of change, and 

 on the other hand, can no longer subsist with a certain degree of 

 climatological change. If in a more remote geographical distance 

 the more important climatological conditions which these genera 

 require a)"e repeated, we may, perhaps, find in another part of 

 the globe a second species ; and this generally explains the orign 

 of the species which have been termed representative (rv'A^r/VVi'WiA' 

 Artcn). A precisely similar climate, however (exactly the same 

 complication of the very varied phenomenon towards which 

 organisms bear themselves receptively), is never repeated in two 

 distant points of the earth's surface ; and this may be taken as 

 the foundation of the absolute unity of centres of vegetation, that 

 is to say, of the proposition that every species in its wanderings 

 has issued from a single birthplace, which does not exclude the 

 possibility of solitary exceptions which might be imagined in 

 plants of less receptivity." 



In all this it appears to me that if the writer refuses to admit 

 of a descent from a common parent, we have a right to ask of 

 him what is the previous organisation upon which he imagines 

 climate to have worked to produce allied species in one region 

 and representative species iu distant regions ? •i\'hat are the pre- 

 vious genera which have ch.anged ? for upon that seems to hinge 

 the whole of his argument in refutation of Asa Gray's hypothesis 

 explanatory of the original connection between the East Asiatic 

 and East American floras. That every species had arisen in one 

 spot, whether by differentiation or by creation, appears now to 

 be tacitly admitted by all. Asa Gray, in accordance with Dar- 

 winian theories, supposes widely spread species to have been, 

 under the different conditions of distant lands, gradually modified 

 in different directions, so as to have produced distinct varieties 

 or representative species ; Grisebach supposes these different con- 

 ditions to have independently produced distinct but similar 

 species, by acting on organisms which had not been one and the 

 same species ; but what else they may have been he seems to 

 think beyond the reach of plausible conjecture. 



