Page:An introduction to pharmacognosy (1905).djvu/19

Rh Beetle family. The group contains a large number of blistering beetles, many of which are coming into use.

In Europe, which is its native habitat, the Spanish fly lives upon plants of the olive family, more particularly on the ash, olive, lilac and privet, and upon the honeysuckle and elder. From these, in the early morning, they are shaken into cloths and killed by the vapor of chloroform, benzine, or other volatile liquid. They are then spread out in the sun and dried.

Description.—Cantharis varies from 15 to 30 mm. ($3⁄5$ to $1 1⁄2$ inches) in length and 6 to 8 mm. ($1⁄4$ to $1⁄3$ inch) in breadth. It is of a brownish cast with coppery green iridescence. The head is somewhat transverse-heart-shaped, the antennae are somewhat thickened, the outer joints being round or oval; the front foot has five joints, the hinder four. The wings are striated and have two or three fine longitudinal stripes or ribs. The smell is peculiar and unpleasant and the taste sharp and burning.

Chemistry.—The active principle has been isolated in the form of a crystallizable body, the anhydride of cantharidic acid, Cantharidin, C11H12O4, and is found in a number of other beetles of allied genera, Lytta, Meloē, Mylabris, Sitaris, and Zonaris, and even the common Colorado potato beetle, Doryphora, 0.5 per cent. It is with difficulty soluble in water, slightly soluble in alcohol, ether, benzol, CS2, whereas in acetone, chloroform, acetic ether, and fatty and ethereal oils it is freely soluble. Cantharidin may be reduced by xylol. Other constituents are fat, 12 per cent., ash, 6.8 per cent.

Adulterations.—Other beetles with which Spanish flies are often mixed can be detected if the size and description given are carefully followed. Those most often used are: