HAIRS, FEATHERS, AND SCALES 37 



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 mi- 

 croscope, 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 

 with angular ends (as represented in the 

 accompanying engraving). By transmitted 

 light they are so transparent and filmy as 

 to be only just discernible; 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 quiver- 

 ing with a motion apparently quite spontaneous, but prob- 

 ably to be referred to slight vibrations of the water in 

 which they float; and each independently of the rest, so 

 as to convey the impression to the observer that each is 

 animated with life, though the scale be taken from a fish 

 some days dead. Owing to this irregular motion, and con- 

 sequent change of position, each spiculum, as it assumes 

 or leaves the reflecting angle, is momentarily brightening 

 or waning, flashing out or retiring into darkness, produc- 

 ing a magic effect on the admiring observer. To this 

 property, I suppose, is to be attributed the beautiful 

 pearly play of light that marks these lovely fishes, as 

 distinguished from the light reflected by a uniformly pol- 

 ished surface. I have found the pearly pigment of the 

 scales to be provided with similar spicula in fishes widely 

 differing in size, structure, and habits; as the Gudgeon and 

 Minnow, the Pike and the Marine Bream. The spicula of 



