September 21, 1893] 



NA TURE 



491 



" natural selection, " "isolation," " the struggle for existence," 

 "the survival of the fittesi," were unheard of and unknown, 

 though many an observer was busied in culling the facts which 

 were being poured into the lap of the philosopher who should 

 mould the first great epoch in natural science since the days of 

 Linnceus. 



It is to the importance and value of field observation that I 

 would venture in the first place to direct your attention. 



My predecessors in this chair have been, of recent years, dis- 

 unguished men who have searched deeply into the abstrusest 

 mysteries of physiology. Thither I do not presume to follow 

 them. I rather come before you as a survivor of the old-world 

 naturalist, as one whose researches have been, not in the labora- 

 tory or with the microscope, but on the wide desert, the moun- 

 tain side, and the isles of the sea. 



This year is the centenary of ihe death of Gilbert White, 

 whom we may look upon as the father of field naturalists. It is 

 true that Sir T. Browne, Willughby, and Ray had each, in the 

 middle of the seventeenth century, committed various observa- 

 tions 10 print ; but though Willughby, at least, recognised the 

 importance of the soft parts in affording a key to classification, 

 as well as the osteology, as may be seen from his observation of 

 the peculiar formations, in the Divers (Colymbitia) of Ihe tibia, 

 with its prolonged procnemial process, of which he has given a 

 figure, or his description of the elongation of the posterior 

 branches of the woodpecker's tongue, as well as by his careful 

 description of the intestines of all specimens which came under { 

 his notice in the flesh, none of these systematically noied the i 

 habits of birds, apart from an occasional mention of their nidi- [ 

 ficatioD, and very rarely do they even describe the eggs. But 

 White was the first observer to recognise how much may be 

 learnt from the life habits of birds. He is generally content with 

 recording his observations, leaving to others to speculate. 

 Fond of Virgilian quotations (he was a fellow of Oriel of the 

 last century), his quotations are often made with a view to 

 prove the scrupulous accuracy of the Roman poet, as tested by 

 his (White's) own observations. 



In an age, incredulous as to that which appears to break the 

 uniformity of nature, but quick to recognise all the phenomena 

 of life, a contrast arises before the mind's eye between the 

 abiding strength of the objective method, which brings Gilbert 

 White in touch with the great writers whose works are for all 

 time, and the transient feebleness of the modern introspective 

 philosophies, vexed with the problems of psychology. The 

 modern psychologist propounds his theory of man and the uni- 

 verse, and we read him, and go on our way, and straightway 

 forget. Herodotus and Thucydides tell a plain tale in plain 

 language, or the Curate of Selborne shows us the hawk on the 

 wing, or the snake in the {jrass, as he saw them day by day, 

 and, somehow, the simple story lives and moves him who reads 

 it long after ihe subtleties of this or that philosophical theory 

 have had their day and passed into the limbo of oblivion. But, 

 invaluable as has been the example of Gilbert White in teach- 

 ing us how to observe, his field was a very narrow one, circum- 

 scribed for the most part by the boundaries of a single parish, 

 and on the subject of geographical distribution (as we know it 

 now) he could contribute nothing, a subject on which even the 

 best explorers of that day were strangely inobservant and in- 

 exact. A century and a half ago, it had not come to be recog- 

 nised that distribution is, along, of course, with morphology 

 and physiology, a most important factor in determining the 

 facts of biology. It is difficult to estimate what might have 

 been gained in the case of many species, now irreparably lost, - 

 had Forster and the other companions of Captain Cook, to say 

 nothing of many previous voyagers, had the slightest conception 

 of the importance of noting the exact locality of each specimen 

 they collected. They seem scarcely to have recognised the 

 specific distinctions of the characteristic genera of the Pacific 

 Islands at all, or if they did, to have dismissed them wiih the 

 remark, " On this island was found a flycatcher, a pigeon, or a 

 parrot similar to those found in New Holland, but with white 

 tail-feathers instead of black, an orange instead of u scarlet breast, 

 or red shoulders instead of yellow. ' As we turn over the pages 

 of Latham or Shaw, how often do we find for locality one of 

 the islands of the South Sea, and, even where the locality is 

 given, subsequent research has proved it erroneous, as ihougli 

 the specimens had been subsequently ticketed ; Le Vaillant de- 

 scribed many of his South African birds from memory. Thus 

 Latham, after describing very accurately Rhipidura Jlaliellifera, 

 from the south island of New Zealand, remarks, apparently on 



NO. 1247, VOL. 48] 



Forster's authority, that it is subject to variation ; that in the 

 island of Tanna anoilier was met with, with a different tail, &c., 

 and ihat there was another variety in ihe collection of Sir 

 Joseph Banks. Endless perplexity has been caused Ly ihe 

 Psiitaciis fygnmus of Gmelin (of which Latham's type is at 

 Vienna) being slated in the inventory as from Botany Bay, by 

 Latham from Olaheite, and in his book as inhabiting several of 

 ihe islands of the South Seas, and now it proves to be the 

 female Psittaciis palmartivi from the New Hebrides. These 

 are but samples of the confusion caused by the inaccuracies of 

 the old voyagers. Had there been in Ihe first crew who landed 

 on the island of Bourbon, I will not say a naturalist, but even a 

 simple-hearted Leguat, to tell the artless tale of what he saw, 

 or had there been among the Poituguese discoverers of Mauri- 

 tius one who could note and describe the habits of its birds with 

 the accuracy with which a Poullon could record Ihe ways and 

 doings of our Lepidoptera, how vastly would our knowledge of 

 a perished fauna have been enriched ! It is only since we 

 learned from Darwin and Wallace the power of isolation in Ihe 

 differentiation of species, that special attention has been paid lo 

 ihe peculiarities of insular forms. Here the field naturalist 

 comes in as the helpful servant of the philosopher and the sys- 

 lematist, by illustrating the operation of isolation in the dif- 

 ferentiation of species. I may lake the typical examples of 1 wo 

 groups of oceanic islands, differing as widely as possible in iheir 

 position on the globe, the Sandwich Islands in the centre of the 

 Pacific, thousands of miles from the nearest coniinent, and ihe 

 Canaries, within sight of the African coast ; but agreeing in 

 this, that both are iruly oceanic groups, of 'purely volcanic 

 origin, ihe ocean depths close to the Canaries, and between the 

 different islands, varying from 1500 to 2C0O fathoms. In the 

 one we may study the expiring relics of an avifauna completely 

 differentiated by isolation ; in the other we have the opporlu- 

 nily of tracing ihe incipient stages of the same proce.'-s. 



"The Sandwich Islands have long been known as possessing! 

 an avifauna not surpassed in interesting pcculiarily by llial o 

 New Zealand or Madagascar ; in fact, it seems as though 

 their vast distance from the continent had intensifitd the 

 influences of isolation. There is scarcely a passerine 

 bird in its indigenous fauna which can be referred to any 

 genus known elsewhere. But, until the very recent re- 

 searches of Mr. Scott Wilson, and the explorations of the 

 Hon. W. Rothschild's collectors, it was not known ihat 

 almost every island of the group possessed one or more repre- 

 sentatives of each of these peculiar genera. Thus, every island 

 which has been thoroughly explored, and in which any extent 

 of the primeval forest remains, possesses, or has possessed, ils 

 own peculiar species of Hemignathus, Himatioiie, Phccotnis, 

 Acrnloceicus, Loxops, Lrepanis, as well as of the massive- 

 beaked finches, which emulate the Ceospiza of the Galapagos. 

 Prof. Newton has shown that while ihe greater number of these 

 are probably of American origin, yet the South Pacific has 

 contributed its quota to this museum of ornithological rarities, 

 which Mr. Clarke very jusily proposes to make a distinct biolo- 

 gical sub-region. 



That each of the islands of this group, however small, should 

 possess a flora specifically distinct, suggests thoughts of the vast 

 periods occupied in their differentiation. 



Jn the Canary Islands, either because they are geologically 

 more recent, or because of their proximity to the African coast, 

 which has facilitated frequent immigrations from the continent, 

 the process of differentiation is only partially accomplished. 

 Yet there is scarcely a resident species which is not more or less 

 modified, and this modification is yet further advanced in the 

 westernmost islands than in those nearest lo Africa. In Fuer- 

 lavenlura and Lanzarote, waterless and treeless, there is Utile 

 change, and the fauna is almost identical with that of the neigh- 

 bouring Sahara. There is a whin-chat, Pratimola ilacotia, 

 discovered by my companion, Mr. Meade-Waldo, peculiar 10 

 Fuertaventura, which may pcsibly be found on the opposite 

 coast, though it has not yet been met with by any collectors 

 there. Now, our whin-chat is a common winter visitant all 

 down the West African coast, and it seems probable that isola- 

 tion has produced the very marked characters of the Canaries 

 form, while the continental individuals have been restrained 

 from variation by their frequent association with their migratory 

 relations. A similar cause may explain why the blackbird, an 

 extremely common resident in all the Canary Islands, has not 

 been modified in the least, since many migratory individuals of 

 the same species sojourn every winter in the islands. Or lake 



