| OCR Text |
Show 244 JJAR WINIANA. Facts like these, which suggest grave diversification under long lapse of time, are well supplemented by those which essentially demonstrate a slighter diversification of ·many species over a wide range of space; whether into species or races depends partly upon how the naturalist uses these terms1 partly upon the extent of the observations, or luck in getting together intermediate forms. The researches of Prof. Baird upon the birds of this continent afford a good illustration. A great number of our birds which have been, and must needs have been, regarded as very distinct species, each mainly with its own geographical area, are found to mingle their characters along bordering lines; and the same kinds of differences (of coloration, form, or other) are found to prevail through the species of each region, thus impressing upon them a· geographical facies. Upon a submergence of the continent, reducing these several regions to islands sufficiently separated, these forms would be unquestioned species. Considerations such as these, of which a few specimens have now been adduced (not general speculations, as the unscientific are apt to suppose), and trials of the new views, to see how far they will explain the problems or collocate the facts they are severally dealing with, are what have mainly influenced working naturalists in the direction of the provisional acceptance of the derivative hypothesis. They leave to polemical speculators the fruitless discussion of the question whether all species came from one or two, or more; they· are trying to grasp_ the thing by the near,· not by the farther end, and to ascertain, first of all, ATTITUDE OF WORKING NATURALISTS. 245 w~ether it is probable or provable that present species are descendants of former ones which were like them but less a.nd. less like them the farther back we go. ' And It IS worth noting that they all seem to be utterly unconscious of wrong-doing. Their repugnance to novel hypotheses is. only the natural and healthy one. A change of a wonted line of thought is not made without an effort, nor need be made without adequa~e occasion. Some courage was required of the man who first swallowed an oyster from its shell; and of most of us the snail would still demand more. .As the unaccustomed food proves to be good and satisfying, and also harmless, we may come to like it. That, however, which many good and eminent natural~ sts find to be healthful and reasonable, and others mnocuous, a few still regard as most unreasonable and harmful. At present, we call to mind only two who not only hold. to the entire fixity of species as an axiom or ~ co~firn:ed principle, but also as a dogma, and who mamta~n, ei.ther expressly_ or implicitly, that the logical antithes1s to the creatiOn of species as they are, is not by law (which implies intention), but by chance. A recent book by one of these naturalists or rather by a geologist of eminence, the ''Story of the Earth ~nd Man," by Dr. Dawson, is now before us. The title is too near that of Guyot's "Earth and Man " with the publication of which popular volume that di~tinguished physical naturalist commenced his career in this country; and such catch-titles are a sort of trade-mark. As to the nature and merits of Dr. Dawson's work, we have left ourselves space only to · say : 1. That it is addressed ad populum, which renders it rather the |
