These questions have been answered alternately in the different senses which they admit of. Unfortunately these solutions have too often been influenced by considerations entirely foreign to science. It has been thought necessary to adopt either the one or the other in the name of dogma or philosophy, and this question has been confounded with that of monogenism and polygenism, without seeing that upon this particular point the two doctrines must lead anyone who remains faithful to the data of science to the same result. Science has already been shown to be our only possible guide; let us examine her teaching on this subject. II. The doctrine which admits the multiplicity of the geographical origins of man, has been more frequently asserted, than sustained by more or less serious arguments. Agassiz is the only naturalist who has developed and defined it, by supporting it with general data. We must, therefore, first examine these data. A very short account will explain the reasons why I must, with regret, oppose one of the men whose learning and character I have always held in the highest estimation. There are singular points of resemblance, and no less striking contrasts between Agassiz and the most extravagant disciples of Darwin. The illustrious author of the _Essay on Classification_ is as exclusive a morphologist as the latter; neither in his opinion nor in theirs, does the idea of _filiation_ form any connection with that of _species_; he declares, as they do, that the questions of crossing, of constant or limited fertility, have no real interest. We are justified in attributing these opinions, so strange in such an eminent zoologist as Agassiz, to the nature of his early works. It is well known that he commenced his career with his celebrated researches upon fossil fishes. We have already remarked upon the influence which is almost inevitably exercised by fossils, where form alone has to be considered, where nothing calls attention to the genealogical connection of beings, and where we meet with neither parents nor offspring.