The evidences are the same as those adduced by Darwin and before his time, but they have been multiplied and more sharply defined:—namely, that the forms of life can be arranged in an ascending scale of evolution, both in their morphological and their physiological aspects, both as regards the general type and the differentiation of individual organs and particular characters, bodily and mental. All the rubrics used by Darwin in this connection, from comparative anatomy, from the palæontological record itself, and so on, have been filled out with ever-increasing detail. Palæontology, in particular, is continually furnishing new illustrations of descent and new evidence of its probability, more telling perhaps in respect of general features and particular groups than in regard to the historical process in detail. For certain species and genera palæontology discloses the primitive forms, discovers “synthetic types” which were the starting-point for diverging branches of evolution, bridges over or narrows the yawning gulfs in evolution by the discovery of “intermediate forms”; and, in the case of certain species, furnishes complete genealogical trees. The same holds true of the facts of comparative anatomy, embryology, and so on. In all detailed investigations into an animal type, in the study of the structure, functions, or the instincts of an ant, or of a whale or of a tape-worm, the standpoint of the theory of descent is assumed, and it proves a useful clue for further investigation.