14 THE BUTTERFLIES OF THE BRITISH ISLES. 



the horny substance of which the chrysalis shell is formed, and 

 this was adverted to when discussing the chrysalis stage as a 

 varnish-like ooze. As seen on the wings, the scales are flat- 

 tened and the upper and under sides are then almost, or quite, 

 brought together. They are attached in lines on the membrane 

 or covering of the wing by short stalks which fit into sockets in 

 the membrane. The arrangement of the scales, which has often 

 been stated to resemble that of the slates on a roof, is shown in 

 Fig. 10. 



Colour is chiefly due to pigment contained in the scale or 

 adhering to the interior of its upper side. Pigments, according 

 to Mayer, are derived, by various chemical processes, from the 

 blood while the butterfly is still in the chrysalis. Some scales 

 have minute parallel lines (strics) on their upper sides, and rays 

 of light falling on these are turned aside or broken up, and so 

 produce changes in the colouring of a wing, according to the 

 angle from which it is looked at. 



The males of many kinds of butterfly have special scales, 

 which are known as androconia, or plumules. It is believed 

 that these are scent organs. Whatever their particular use may 

 be to the possessor, these androconia enable the entomologist 

 to distinguish male specimens from females with great certainty. 

 In the Fritillaries they are placed on one or more of the median 

 nervules (veins 2, 3, and 4) of the fore wing. In the Meadow 

 Brown and its kindred they form brands on the disc of the fore 

 wing. In the Skippers they are placed in a fold of the costa in 

 some species, and in other species they are clustered together, 

 into more or less bar-like marks, about the middle of the fore 

 wings. Some of these various shaped " plumules " are shown 

 in the illustrations. 



In the foregoing sketch of the life cycle of a butterfly, the 

 object has been to condense as much necessary information as 

 possible into a limited space. Many matters of importance to 

 the student have not been touched on, but it was considered 



