ESTFUSOEIA. 465 



pet of the clearest glass, with a rounded extremity, and 

 with the bese affixed to the weed, from whicli it stands 

 \ip erect. Within the expanded part of the trumpet 

 there is a turbid mass, with a perfectly defined outline, 

 from several points of which proceed radiating pencils 

 or tufts of long, straight, stiff, elastic filaments, like 

 threads of spun glass, varying greatly in length, and 

 each terminated by a little knob of the same material. 

 The tout ensemble of this object is very attractive and 

 beautiful, and its history is a tale of marvels. 



1^0 wonder that Ehrenberg, supposing this form to 

 be an independent animal, gave it a generic and spe- 

 cific name. He called it Acineta mystacina. For who 

 would have suspected that this stiff and motionless ob- 

 ject, with its tufts of flexible but inanimate threads, 

 had any connexion with the sprightly vases which we 

 have been examining ? Yet it is the same animalcule, 

 in what we may, with a certain liberty of phrase, call 

 its clirysalis condition ! 



The histoiy of the Vorticella, as it has been elabo- 

 rately worked out by Dr. Stein, exhibits phenomena 

 analogous to those marvellous changes which we lately 

 considered under the appellation of the Alternation of 

 Generations. Large individuals withdraw their circle 

 of cilia, close up the mouth, and become , globular, 

 and then secrete from their whole surface a gummy 

 substance, which hardens into a spherical transparent 

 shell, inclosing the VortiGella in its cavity, in the form 

 of a simple vesicle. Within this vesicle is seen the 

 band-shaped nucleus, nnchanged, and what was the 

 contractile bladder, which, however, no longer con- 

 tracts. 



By and by this torpid VorUcella enlarges itself ir- 

 20* 



