310 



EVENINGS AT THE MICBOSCOPE. 



You have doubtless observed, while gazing on the ani- 

 mal, a peculiar glittering appearance along its sides, 

 mingled in certain lights with brilliant rainbow-reflections. 

 Now let us take an opportunity, when it approaches the 

 side of the glass, to examine this appearance with a lens. 

 The globe, you see, is marked by longitudinal bands, eight 

 in number, set at equal distances, and ranging like meri- 

 dians, except that they do not quite reach to either pole. 

 These bands are the seats of the motile organs, which are 

 highly curious, and in some sort peculiar. 



Each band is of considerable width in the middle, but 

 becomes narrower towards the extremities. It carries a 



number — usually from twenty to thirty — of fiat thin mem- 

 branous fins, set at regular distances, one above the other, 

 which may be considered as single horizontal rows of cilia, 

 agglutinated together into flat plates. Each plate has a 

 rapid movement up and down, from the line of its inser- 

 tion into the band, as from a hinge, and thus striking the 

 water downwards, like a paddle. The whole band may be 

 likened to the paddle-wheel of a steamer, except that the 



