Who does not admire the extraordinary splendour, the vivacity, the prodigious variety of colours of these brilliant inhabitants of the air? Some amateurs have devoted to the purchase of certain butterflies large sums of money. "Diamonds," says Réaumur on the subject, "have perhaps beauties no more real than those of a butterfly's wings; but they have a beauty which is more acknowledged by the world in general, and which is more recognised in commerce." The essential character of butterflies and moths makes them very easily recognisable among all other insects. All have four wings, which are covered with scales, that communicate to them the brilliant colours with which they are decorated. It is these scales which adhere to the fingers when we seize one of these charming creatures. [Illustration: Fig. 133.--Different forms of the scales of Butterflies, after Réaumur.] For a long time this dust was thought to be formed of very small feathers, but Réaumur showed that it is composed of little scales. Their form varies singularly, as we may see in Fig. 133, borrowed from the Memoirs of Réaumur,[45] which represents the different forms of the scales which cover the wings of Lepidoptera. M. Bernard Deschamps has closely studied them. According to this naturalist, they are composed of three membranes, or plates, superposed one on the other, of which the first is covered with granulations of a rounded form, which give to these scales their splendid and varied colours; the second plate is covered with silk, forming sometimes curious designs; the third plate, viz., that which is applied to the membrane of the wing, has the peculiar property of reflecting colours the most brilliant and the most varied, although the surface of the scales visible to the eye is often dull and colourless. [45] Tome i., planche 7, Figs. 1 à 23. "Supposing," says M. Bernard Deschamps, "that a painter was possessed of colours rich enough to represent on canvas with all their splendour, gold, silver, the opal, the ruby, the sapphire, the emerald, and the other precious stones which the East produces, that with these colours he formed all the shades which could result from their combination, one might affirm without the chance of contradiction, that he would have none of these colours and of their various shades, whatever might be the number, which could not be discovered by the microscope on part of the scales of the Lepidoptera, which Nature has been pleased to conceal from our gaze." [Illustration: Fig. 134.--Portion of the wing of a Moth (_Saturnia pavonia major_), magnified.] Each of these scales adheres to the membrane of the wing by a small tube, which is solidly fixed to it. Réaumur has called our attention to the admirable arrangement of these scales, which are disposed like those of fish, that is to say, in such a manner that those of a row shall partially overlap those in the following one.