24 



EVENING8 AT THE MICEOSCOPE. 



deposits from beneath ; but that, after a few have been 

 deposited, they begin to slit, probably by contraction 

 in becoming solid ; that the lower layer is formed after 

 each upper one is hardened, exceeding its length by a 

 little, and filling up the slit ; that this lower layer be- 

 comes the upper layer of the next course, slitting, and 

 turning up its terminal edge as it hardens ; that then 

 the lower layer is deposited on this, filling up the slit 

 as before ; and that this process goes on as long as the 

 fish lives. 



It is curious that, in the scales of the Pike, the por- 

 tions thus separated by slitting, instead of expanding 

 and 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 (5), which has only 



^ ( 



SCALES OF PIKE. 



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, de- 

 pends not on the scales themselves, but on a soft layer 



