HAIRS, FEATHEKS, AND SCALES. 



25 



of pigment spread over their inner surface, and seen 

 tlirough their translucent substance. On carefully de- 

 taching a scale, we see on the under side, opposite to 

 that portion only which was exposed (all the concealed 

 parts being colourless), a layer of soft gleaming sub- 

 stance., easily separable, either silvery or golden, ac- 

 cording to the hue of the fish. If now we remove a 

 small portion of this substance with a fine needle, and 

 spread it on a plate of thin glass, we shall find, by the 

 aid of the microscope, that it consists of two distinct 

 substances ; the one giving the colour, the other the 

 metallic lustre. With a power of 300 diameters, the 

 former is seen to be a layer of loose membranous cells 

 of an orange colour, in what are properly called the 

 Gold-fishes, and whitish or pellucid in the Silver-fishes. 

 If we now add a minute drop of water to the mass, and 

 gently agitata it with the point of a needle, and again 

 submit it to the microscope, we shall have a beautiful 

 and interesting spectacle, The water around the mass 

 is seen to be full of an infinite number of flat spicula or 

 crystals, varying much in size, but of 

 very constant form, a flat oblong prism 

 with angular ends (as represented in 

 the accompanying engraving). By 

 transmitted light they are so transpa- 

 rent and filmy as to be only just dis- 

 cernible; but by reflected light, and 

 especially under the sun's rays, they 

 flash like plates of polished steel. But 

 what appears most singular, is that 

 each spiculum is perpetually vibrating and quivering 

 with a motion apparently quite spontaneous, but prob- 

 ably to be referred to slight vibrations of the water in 

 2 



SPICTTLA OE GOLD- 

 FISHES BGALE. 



