Réaumur was neither an anatomist nor a systematist, at least he gained no distinction in either of these branches of biology. No biological laboratory had been dreamt of in his day; he lacked the manipulative skill of Swammerdam or Lyonet; he was no draughtsman, and had to engage artists to draw for him. One qualification of the first importance, however, he possessed in a high degree, the scientific mind. As he watched the acts of an insect, questions at once sagacious and practical suggested themselves in abundance, and these questions he set himself to answer in the best possible way—viz., by observation and experiment. In close attention to the activities of living things his ingenuity and patience found a boundless sphere of exercise. Moreover all that he had seen he could relate in a simple but picturesque manner, using the language familiar to the best French society in the generation next after Madame de Sévigné. Diffuse but clear, amusing but never frivolous, he won and kept the attention of a multitude of readers, the best of whom were incited to adopt his methods or to pursue inquiries which he had indicated. His greatest successes were won in observing and interpreting the natural contrivances of insects, the means by which they get their food and provide for their safety; their transformations, instincts, and societies. Kirby and Spence, which is still one of the best popular accounts of insects in English, is largely based upon Réaumur; so are other well-known treatises, in which the debt is less frankly acknowledged. Réaumur greatly enlarged the knowledge of all kinds of insects except the beetles and Orthoptera, which he did not live to describe, and to this day his _Histoire des Insectes_ is a work of fundamental importance, with which every investigator of life-histories is bound to make himself acquainted. No abstract of Réaumur's _Histoire des Insectes_ is possible, but we may at least give one example of his mode of treatment. Let us select his account of the proboscis of a moth, the first full account that was ever given. He tells us that all moths have not an effective proboscis, though he does not explain how some of them can dispense with what seems so necessary an organ; this omission has been made good by later entomologists. The proboscis, he goes on, springs from the head, just between the compound eyes. When at rest, it takes up very little room, for it is spirally rolled, like a watch spring; in some cases it makes as few as one and a half or two turns, in others as many as eight or ten; the base is often concealed by a pair of hairy palps, which serve as feelers. Careful study of a moth as she flits from flower to flower shows that she alights on the plant, unrolls her proboscis, passes it into the corolla, withdraws it, perhaps coils it for an instant, and then plunges it again into the tube. When this manœuvre has been repeated several times, the moth flies off to another flower.