36 EVENINGS AT THE MICROSCOPE 



leaving spaces to be filled up, actually close over each 

 other, the divided parts overlapping considerably, as you 

 may see in these specimens. The left-hand scale (a) is 

 from the back ; the central one (ft), which has only a deep 

 narrow incision instead of a tube, is from the lateral line; 

 and the third (c) is from the belly of the fish. 



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 constitutes 

 the beauty of these lovely fishes depends not on the scales 

 themselves, but on a soft layer of pigment spread over 



SCALES OF PIKE. 



their inner surface, and seen through their translucent sub- 

 stance. On carefully detaching a scale, we see on the un- 

 der side, opposite to that portion only which was exposed 

 (all the concealed parts being colorless), a layer of soft 

 gleaming substance, easily separable, either silvery or 

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

 move 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 color, the other the metal- 

 lic lustre. With a power of 300 diameters, the former is 

 seen to be a layer of loose membranous cells of an orange 

 color, in what are properly called the Gold-fishes, and 



