A examplc of the effects of environment and chang-ed conditions of life upon the forms of animáis is f urnished by a species of partridg-e living1 in the Canary islands. About four hundred .years ag-o the Spaniards introduoed the red-leg-g-ed partridg-e from Europe into these islands, and the bird has continued to. flourish there; but, as recent examination proves, it has underg-one modifications clearly broug-ht about by the conditions under which it lives. lts back has turned from russet color to gray. This looks like a case of protective coloration, since the bird passes its life amid gray volcanic rocks. Then its beak has become one-fourth long-er and thicker than that of its ancestors and of its European relatives, and its leg-s also have increased in leng-th and grown stouter. These chang-es are exactly such as were needed to suit it to the life thit it is novv compelled to lead amid the rocks and on the mountain sides of the islands, where a more vig-orous physical development is required than was needed upon the plains of England and France. As has been remarked, if such chang-es can be wroug-ht by nature in the animal form in four hundred j-ears, wliat mig-ht not have been accomplished in four hundred centuries?