_Grapta satyrus._ | | 34. _Pyrameis huntera._ | | 35. _Pyrameis atalanta._ | | 36. _Vanessa milberti._ | | 37. _Pyrameis cardui._ | | 38. _Grapta comma._ | | | | [Illustration PLATE III.] | +--------------------------------------------------------------+ If a wing is examined with the naked eye, or even with a lens, a clear conception of the structure of the veins can rarely be formed. Therefore it is generally necessary to remove from the wings the scales which cover them, or else bleach them. The scales may be removed mechanically by rubbing them off. They may be made transparent by the use of chemical agents. In the case of specimens which are so valuable as to forbid a resort to these methods, a clear knowledge of the structure of the veins may be formed by simply moistening them with pure benzine or chloroform, which enables the structure of the veins to be seen for a few moments. The evaporation of these fluids is rapid, and they produce no ill effect upon the color and texture of the wings. In the case of common species, or in the case of such as are abundantly represented in the possession of the collector, and the practical destruction of one or two of which is a matter of no moment, it is easy to use the first method. The wing should be placed between two sheets of fine writing-paper which have been moistened by the breath at the points where the wing is laid, and then by lightly rubbing the finger-nail or a piece of ivory, bone, or other hard substance over the upper piece of paper, a good many of the scales may be removed. This process may be repeated until almost all of them have been taken off. This method is efficient in the case of many of the small species when they are still fresh; in the case of the larger species the scales may be removed by means of a camel's-hair pencil such as is used by painters. The chemical method of bleaching wings is simple and inexpensive. For this purpose the wing should be dipped in alcohol and then placed in a vessel containing a bleaching solution of some sort. The best agent is a solution of chloride of lime. After the color has been removed from the wing by the action of the chloride it should be washed in a weak solution of hydrochloric acid. It may then be cleansed in pure water and mounted upon a piece of glass, as microscopic slides are mounted, and thus preserved. When thus bleached the wing is capable of being minutely studied, and all points of its anatomy are brought clearly into view. [Illustration FIG. 38.--Outline of wing, giving names of parts.] [Illustration FIG. 39.--Arrangement of scales on wing of butterfly.]