Vorticellina.'} THE INFUSORIA. 259 



or an achromatic condenser, under the stage, to render it 

 distinct. 



395. VOBTICELLA uebulifera (V. nebulifera et conval- 

 laria, M.) The nebulous Vorticella. The body of this 

 creature is in the form of a bell, that part answering to 

 the mouth of the bell being expanded, and the margin 

 fringed with cilii ; the pedicle or stalk, which is about five 

 times the length of the body, is attached to the convex 

 apex, which is rather conical, when the creature is in 

 health, but hemispherical when otherwise. The mouth 

 is situated near the margin, in which place the wreath of 

 cilii is interrupted. These creatures usually congregate 

 together, though each is independent of its neighbour ; for 

 on the approach of any foreign body to one, it withdraws, 

 by coiling up its pedicle, while the others remain stretched 

 out in search of food. By this action the pedicle is not 

 contracted, but merely deflected, by means of the long 

 muscle within it, so that it can form as many as ten coils, 

 like the spring of a bell. The body of the animalcule 

 does not contract or become wrinkled, but the margin of 

 cilii appears sometimes bent inwards. In colour, when 

 seen in masses about the roots of lemna, they appear 

 white. An amplification of 300 diameters is necessary to 

 exhibit the cilii. Longitudinal self- division may often be 

 observed, during which the body becomes broader. 

 Gemmae, or buds, shoot out from the sides of the other 

 species, but have not been noticed in this. Found 

 abundantly on the stalks of lemma and water-plants, even 

 in winter under ice. Length of body l-570th to l-280th. 



396. VORTI.CELLA citrma (M.) The yellow Vorticella. 

 The body is more hemispherical than the preceding, and 



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