THE STORY OF THE UNIVERSE 



are all marked with longitudinal lines, very minute 

 and close, but they mostly bear a central band, and 

 sometimes a marginal one on each side, of spots set in 

 sinuous lines like the bands on a mackerel's back; 

 these are probably composed of pigment-granules. 



The hairs with which the bodies of moths are in- 

 vested are essentially of the same character as the 

 scales which clothe their wings. Here are examples 

 from the glowing sides of the abdomen of that richly 

 colored insect, the cream-spot tiger-moth (Arctia 

 villica). You see they are simple scales, drawn out 

 to an inordinate length and great tenuity; each has 

 its quill-like footstalk, and we may trace on some 

 of them the ribs and transverse dotting, while here 

 we see all intermediate stages between the slenderest 

 hair and the broadly ovate, bluntly pointed scales 

 from the wings. 



You are familiar, of course, with the brilliant 

 little blue butterfly (Polyommatus Alexis) which 

 dances and glitters in the sunshine on waste places 

 in June. Among the scales of ordinary form which 

 clothe the lovely little wings will occur one here and 

 there of a different shape from the rest. Here you 

 may see one; it is much smaller than the average; 

 the footstalk is very long, and the shape of the en- 

 tire scale is that of a battledoor. The ribs are 

 rather few and coarse, and they have this peculiarity, 

 that each rib swells at intervals into rounded dila- 

 tations, each of which has a minute black point in 

 its centre. In some of these battledoor scales there 

 is, near the lower part of the expansion, a crescent 

 of minute pigment-grains. 



