The power and instinct of observation combined with the most consummate skill do not necessarily make a great philosophical naturalist. Leeuwenhoek had all these. They bore admirable fruits, too. We cannot but read the old man's letters to the Royal Society, written, if we remember right, after the age of eighty, with delight and admiration. Those little lenses in their silver mountings, all ground and set and fashioned by his own hand, showed him the blood-globules, and the "pipes" of the teeth, which Purkinje and Retzius found with their achromatic microscopes a century later. We honor his skill and sagacity as they deserve; but a little trick of Mr. Dollond's, applied to the microscopic object-glass, has left all his achievements a mere matter of curious history. Few have been more remarkable for perceiving resemblances and differences than Oken. This is the poetical side of the scientific mind; and he shares with Goethe the honor of that startling and far-reaching discovery, the vertebral character of the bones of the cranium. At this very time the four vertebral cranial bones recognized by Owen are the same Oken has described. But notwithstanding the generous tribute of Mr. Agassiz to his great merits, the writer who assigns special colors to the persons in the Trinity, (red, blue, and green,) and then allots to Satan a constituent of one of these, (yellow,) has drifted away from the solid anchorage of observation into the shoreless waste of the inane, if not amidst the dark abysses of the profane. If the widest range of mental vision, joined, too, with great learning, could make a successful student of Nature, Lord Bacon should have stood by the side of Linnaeus. But open the "Sylva Sylvarum" anywhere and see what Bacon was as a naturalist. "It was observed in the _Great Plague_ of the last yeare, that there were scene in divers _Ditches_ and low _Grounds_ about _London_, many _Toads_ that had _Tailes_, two or three inches long, at the least: Whereas _Toads_ (usually) have no Tailes at all. Which argueth a great disposition to _Putrefaction_ in the _Soile_ and _Aire_." This in that "great birth of time," the "Instauration of the Sciences"! The systematizing or coordinating power is worse than nothing, unless it be supported by the other qualities already mentioned. Darwin had it, and something of what is called genius with it; but where is now the "Zoönomia"?