PDF - Wallace Online

ix THE DEBT OF SCIENCE TO DARWIN 459the cirripedia or barnacles, as well as of a most ingeniousexplanation of the origin and structure of coral-reefs aseries of volumes which were the direct outcome of hisvoyage, and which gave him an established reputation. Evenwhen the great work at last appeared, few could appreciatethe enormous basis of fact and experiment on which it rested,until, during the succeeding twenty years, there appearedthat remarkable succession of works which exhibited a sample(and only a sample) of the exhaustless store of materials andthe profound maturity of thought on which his early volumewas founded. From these various works, aided by some personalintercourse and a correspondence extending over twentyyears, the present writer will endeavour to indicate thenature and extent of Darwin's researches.Studies of Domestic AnimalsAlthough, as we have said, Darwin had early arrived atthe conclusion that allied species had descended from commonancestors by gradual modification, it long remained to him aninexplicable problem how the necessary degree of modificationcould have been effected, and he adds : "It would thushave remained for ever, had I not studied domestic productions,and thus acquired a just idea of the power of selection."These researches, very briefly sketched in the first and partsof the fifth and ninth chapters of the Origin of Species, werepublished at length (after a delay of nine years, owing to illhealth) in two large volumes, with the title Animals and PlantsUnder Domestication; and no one who has not read thesecan form an adequate idea of the wide range and thoroughcharacter of the investigation on which every statement orsuggestion in the former work was founded.The copious references to authorities show us that hemust have searched through almost the entire literature ofagriculture and horticulture, of horse and cattle breeding, ofsporting, of dog, cat, pigeon, and fowl fancying, includingendless series of reviews, magazines, journals of societies, andnewspapers, besides every scientific treatise bearing in anyway on the subject, whether published in this country, on theContinent, or in America. The facts thus laboriously gatheredwere supplemented by personal inquiries among zoologists and