HEX CURASSOW FEEDING YOUNG BIRD, WHICH HAS THE PLUMAGE OF THE HENS OFTHE GLOBOSE CURASSOW, ITS FATHER’S SPECIES
THE MAKING
OF SPECIES
BY DOUGLAS DEWAR, B.A. (Cantab), I.C.S., F.Z.S.
AND FRANK FINN, B.A. (Oxon), F.Z.S., M.B.O.U.
WITH FIFTEEN ILLUSTRATIONS
LONDON: JOHN LANE THE BODLEY HEAD
NEW YORK: JOHN LANE COMPANY MCMIX
Turnbull & Spears, Printers, Edinburgh
PREFACE
Post-Darwinian books on evolutionfall naturally into four classes. I. Thosewhich preach Wallaceism, as, for example,Wallace’s Darwinism, Poulton’sEssays on Evolution, and the voluminous worksof Weismann. II. Those advocating Lamarckism.Cope’s Factors of Evolution and the writings ofHaeckel belong to this class. III. The writingsof De Vries, forming a group by themselves.They advocate the theory that species springsuddenly into being; that new species arise bymutations from pre-existing species. IV. Thelarge number of books of a more judicial nature,books written by men who decline to subscribeto any of the above three creeds. Excellentexamples of such works are Kellog’s DarwinismTo-Day, Lock’s Recent Progress in the Study ofVariation, Heredity, and Evolution, and T. H.Morgan’s Evolution and Adaptation.
All four classes are characterised by defects.
Books of the two first classes exhibit thefaults of ardent partisanship. They formulatecreeds, and, as Huxley truly remarked, “Sciencecommits suicide when it adopts a creed.” The[vi]books which come under the third category havethe defects of extreme youth. De Vries hasdiscovered a new principle, and it is but naturalthat he should exaggerate its importance, and seein it more than it contains. But, as time wearson, these faults will disappear, and the theory ofmutations will assume its true form and fall intoits proper place, which is somewhere betweenthe dustbin, to which Wallaceians would relegateit, and the exalted pinnacle on to which DeVries would elevate it.
In the present state of our knowledge, booksof Class IV. are the most useful to the student,since they are unbiassed, and contain a judicialsumming-up of the evidence for and against thevarious evolutionary theories which now occupythe field. Their chief defect is that they arealmost entirely destructive. They shatter thefaith of the reader, but offer nothing in placeof that which they have destroyed. T. H.Morgan’s Evolution and Adaptation, however,contains much constructive matter, and so is themost valuable work of this class in existence.
Zoological science stands in urgent need ofconstructive books on evolution—books withleanings towards neither Wallaceism, nor Lamarckism,nor De Vriesism; books which shallset forth facts of all kinds, concealing none,not even those which do not admit of explanationin the present state of our knowledge.—It[vii]has been our aim to produce a book of thisdescription.
We have endeavoured to demonstrate thatneither pure Lamarckism nor pure Wallaceismaffords a satisfactory explan