HAIRS, FEATHERS, AND SCALES. 



23 



Let us return now to the scales of our Gold-fish, and 

 examine a highly interesting structure connected with 

 them. The brilliant golden or silvery reflection that con- 

 stitutes the beauty of these lovely fishes, depends not on 

 the scales themselves, but on a soft layer of pigment spread 

 over their inner surface, and seen through theirtranslucent 

 substance. On carefully detaching a scale, we see on the 

 under side, opposite to that portion only which was ex- 

 posed (all the concealed parts being colourless), a layer of 

 soft gleaming substance, easily separable, either silvery or 

 golden, according to the hue of the fish. If now we remove 

 a small portion of this substance with a fine needle, and 



(i 



SCALES OF PIKE. 



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

 of the microscope, that it consists of two distinct sub- 

 stances ; the one giving the colour, the other the metallic 

 lustre. Witha 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 agitate it 

 with the point of a needle, and again submit it to the 

 microscope, we shall have a beautiful and interesting spec- 

 tacle. 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 



