THE MICROSCOPE IN ZOOLOGY. 83 



wings for if you rub the dust off the wings, you will 

 see they are membranes like the tiles on the roof of 

 a house. It is the scales that give the brilliant hues 

 to the wings; one patch being red, another green, 

 another brown or yellow. There is great variety of 

 form in the scales even of the same insect ; those on 

 the wings are generally broad, those on the legs long 

 and slender. Now examine carefully the form of a 



The Gnat and her Boat of Eggs. 



single scale ; you will see that each one is furnished 

 with a short pedicel or foot-stalk ; carefully wash 

 away all the dust off the wing you are examining, and 

 attend to the membrane only, You will see regular 

 rows of small sockets ; into' these sockets the foot- 

 stalks of the scales are fitted. The foot-stalks of the 

 scales vary according to the species. The little azure 

 blue butterfly (Polyommatus Alexis)^ so common in the 

 summer months, will supply you with a form of scale 

 termed "battledore scale," the footstalk of which 

 forms quite a long handle. These scales are marked 

 by longitudinal ribs, which swell into round elevations 



