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of modern thought, that in the fossil fauna of past times, there are many examples of extinct forms of life alongside of many existing in the present day; and that while both may be grouped under genera and species, there is no transition form discoverable bridging over the line which defines the limit of species.
Popular as these speculations have become, in consequence of the charm of the writer's language and the wide scope which the play of thought may, in imagination, reach in reading Professor Darwin's beautiful illustrations of natural selection, they seem to me to want all that could give them firmness or stability. The conclusions, which may possibly be true, with reference to the origin of varieties, cannot be applied to the wider field of the origin of species without some kind of evidence that Nature has worked in this way. Many of her laws are yet unknown. The growth and the decadence of nations are problems which yet await solution. The high culture of European races, as contrasted with the moral degradation of the negro tribes, has not been brought into the domain of any definite law; but, in my judgment, what is popularly known as Darwinianism has not added one new item to our scientific knowledge, and cannot be commemorated as an instance of the real progress of science in a Harveian Oration. I would here broadly assert that no law of Nature
