INFUSORIA. 408 



middle, terminating below in a kind of nipple to which the 

 stalk is attached, and above in a short wide neck with a 

 thickened rim. This last is highly sensitive and con- 

 tractile ; its inner edge is set round with a circle of 

 vibratile cilia, which, when in full play, produce a pair of 

 small circular whirlpools over two opposite points of the 

 brim. The cilia themselves cannot be distinguished, but 

 their optical expression is curious. At the two opposite 

 points of the circular margin, as seen in perspective when 

 slightly inclined towards the observer, viz., at those points 

 where the cilia, from their position with regard to the eye, 

 would be crowded together, there are seen two dark 

 dashes, representing, doubtless, two ciliary waves, but 

 which have all the appearance of tangible objects, some- 

 times withdrawn, sometimes protruded, and often vibrated 

 with a rapid snatching movement. 



These vases are of the usual appearance in Infusoria. 

 Their substance is the clear transparent colourless sarcode, 

 but it contains within it more or less of the cloudy nebulous 

 matter which we have been lately familiar with. There 

 are several globular vesicles or vacuoles, some ready to 

 imbibe colour from pigment, and others already occupied 

 with brown food; while in each case we see, near the 

 centre of the vase, a longish body of clear granular texture, 

 which is called the nucleus, and which seems to play an 

 essential part in the vital economy of the animal. 



The movements of a group such as that we are looking 

 at are very sprightly and pleasing. The vases turned in 

 all directions, some presenting their mouths, some their 

 sides, some their bases, to the eye ; inclined at various 

 angles from the perpendicular, and bending in diverse 

 degrees upon the extremity of their stalks ; swaying slowly 

 and gracefully to and fro, as driven hither and thither by 

 the ciliary currents ; and, above all, ever flying up and 

 down within the length of their radius, as a bird when 

 confined by a string ; all these circumstances impart a 

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