94 Objects for the Microscope. 



with these beautiful scales which require high and good 

 powers to see distinctly. 



A few words may be added on the appearance which 

 Podura scales should present as a test object. Under a 

 medium power they resemble watered silk ; light and dark 

 lines wave across the scale in irregular bands ; but with 

 better definition every dark band should be resolved into 

 rows of short lines, thick at one end, and very fine at the 

 other. Yet these apparent lines are not lines. We must 

 have a higher power, a good quarter-inch lens, and then 

 with careful management of light always a most impor- 

 tant thing we shall see that the apparent lines are really 

 spaces between the wedge-like particles which make up 

 the layer or upper surface of the scale. As a test object it 

 is out of fashion ; the dots of the Pleurosigma and the striae 

 of Grammatophora and Pygidium of a flea being preferred 

 by many scientific observers. 



ELYTRON OF DIAMOND BEETLE. 



A most beautiful object, to be looked at with reflected 

 light that is as an opaque. These brilliant spots are 

 groups of scales, fashioned precisely like those of a butterfly's 

 wing, but owing to their iridescence, to the peculiar thinness 

 of the upper layer and the reflecting power of the secon- 

 dary layer, the colour changes like that on a soap-bubble 

 by the varied position of the light, the dark cell in which 

 the scales are set adding to their brilliancy. The Diamond 

 Beetle is one of the weevil tribe, and a native of South 

 America; but we have smaller Diamond Beetles in our 

 own country, and the Curculio of the oak and of the beech, 

 a little green and gold weevil, by no means rare on nettle- 

 plants, is quite as beautiful under the microscope, having 

 the same kind of scales, set in dark cup-like recesses on 

 its elytra. 



FEET AND LEGS OF INSECTS. 

 FOOT OF SYEPHUS. 



Although the feet are better studied with the leg and 

 upon the whole insect, yet as those specimens are not so 



