nothing authorises us to believe that the laws existing at the origin of life on our planet have since been abrogated, we see that, if we must necessarily conclude a spontaneous primitive genesis, there is nothing irrational in admitting, until we know farther on the subject, the persistence of the phenomenon. Let us return to the subject of species, which, however, we did not quite leave in speaking on the subject of spontaneous generation. Isidore Geoffroy wishes to advance slowly in this matter, and only when facts become patent to all. But he himself has more than once shown, by a noble example, the benefits which science obtains by casting itself beyond the limits of fact, provided that care is taken at first not to give more than a simple hypothetical value to that which we may desire to bring forward. In the question which occupies our attention, we must embrace at one glance the whole animal kingdom since its commencement, in order to deduce the truth of facts which have been observed; only then these relations, for which science so ardently seeks, would appear in their proper light. On account of this impossibility, we must hope for some more enlightenment, chiefly from geology, and perhaps from experiments. “How many facts would be necessary,” said Buffon, “in order to pronounce authoritatively, or even to conjecture? How many experiments are to be tried in order to discover these facts, to acknowledge them, or even to anticipate them by well-founded conjectures?” Two opinions on the origin of species deserve to be noticed,--those of Cuvier and Lamarck. This last held Buffon’s opinions at the end of his career, and it ought to find in Étienne Geoffroy a defender even more powerful in our eyes than Isidore Geoffroy himself; and especially Darwin, to whom belongs the merit, however, of having propagated, in his popular work, the ideas of Lamarck.