Fleischmann’s book strengthens the impression gained elsewhere, that a general survey of the domain of life as a whole gives force and convincingness to the Theory of Descent, while a study of details often results in breaking the threads and bringing the difficulties into prominence. But the same holds true of many other theoretical constructions, and yet we do not seriously doubt their validity. (Take, for instance, the Kant-Laplace theory, and theories of ethnology, of the history of religion, of the history of language, and so on.) And it is quite commonly to be observed that those who have an expert and specialist knowledge, who are aware of the refractoriness of detailed facts, often take up a sceptical attitude towards every comprehensive theory, though the ultimate use of detailed investigation is to make the construction of general theories possible. Fleischmann does exactly what, say, an anthropologist would do if, under the impression of the constancy and distinctiveness of the human races, which would become stronger the more deeply he penetrated, he should resignedly renounce all possibility of affiliating them, and should rest content with the facts as he found them. Similarly, those who are most intimately acquainted with the races of domesticated animals often resist most strenuously all attempts, although these seem to others a matter of course, to derive our “tame” forms from “wild” species living in freedom. But to return. Even where the Theory of Descent is recognised, whether fully or only half-heartedly, the recognition does not always mean the same thing. Even the adherents of the general, but in itself quite vague view that a transformation from lower forms to higher, and from similar to different forms, has taken place, may present so many points of disagreement, and may even stand in such antagonism to one another, that onlookers are apt to receive the impression that they occupy quite different standpoints, and are no longer at one even in the fundamentals of their hypotheses.