Page:Popular Science Monthly Volume 37.djvu/331

Rh it is with, the other animals and with a large proportion of the plants. . .. The naturalist, looking at the inhabitants of these volcanic islands in the Pacific, feels that he is standing on American land."

The question, then, is this: If these species have been created as we find them on the Galapagos, why is it that they should all be very similar in type to other animals, living under wholly different conditions, but on a coast not so very far away? And again, why are the animals and plants of another cluster of volcanic islands—the Cape Verde Islands—similarly related to those of the neighboring coast of Africa, and wholly unlike those of the Galapagos? If the animals were created to match their conditions of life, then those of the Galapagos should be like those of Cape Verde, the two archipelagoes being extremely alike in respect to soil, climate, and physical surroundings. If the species on the islands are products of separate acts. of creation, what is there in the nearness of the coasts of Africa or Peru to influence the act of creation so as to cause the island species to be, as it were, echoes of those on shore?

If, on the other hand, we should adopt the obvious suggestion that both these clusters of islands have been colonized by immigrants from the mainland, the fact of uniformity of type is accounted for, but what of the difference of species? If the change of conditions from continent to island may on the island cause such great and permanent changes as to form new species from the old, why may not like changes take place on the mainlands as well as on the islands? And if possible on the mainland of South America, what evidence have we that species are permanent anywhere? May they not be constantly changing? May not what we now consider as distinct species be only the present phase in the changing history of the series of forms which constitutes the species?

The study of these and many similar facts can lead to but one conclusion:

These volcanic islands rose from the sea destitute of land life. They were settled by the waifs of wind and of storm, birds and insects blown from the shore by trade winds, lizards carried on drift-logs and floating vegetation. Of these waifs few came perhaps in any one year, and few perhaps of those who came made the islands a home; yet, as the centuries passed on, suitable inhabitants were found. That this is not fancy we know, for we have the knowledge of many similar transfers. Every one who has approached our eastern shores by sea in the face of a storm will realize this. Hosts of land birds—sparrows, warblers, chickadees, and even woodpeckers—are carried out by the wind, a few falling exhausted on the decks of ships, a few others falling on