INFUSOEIA. 467 



■wai'ds. The Acineta now collapses and disappears, 

 having done its office, while the embryos shoot hither 

 and thither in newly acquired freedom. It is assumed, 

 on pretty good grounds, that these embryos soon be- 

 come fixed, develop stalks, which are at first not con- 

 tractile, and gradually grow into perfect VorHcellcB 

 small at the beginning, but capable of self- division, and 

 of passing into the Acineta stage, and gradually attain- 

 ing the full size of the race. 



Some forms of the same family, Vorticelladce, are 

 interesting as dwelling in beautiful crystalline houses, 

 of various shapes, always elegant. All these have 

 been ascertained to pass through the same or similar 

 Acineta stages. Cothurnia imieriis is one of the 

 prettiest of these. The cell is of an elegant ampulla- 

 like form, perfectly transparent and colourless, set on 

 a stiff foot, or short pedicle, which shows many trans- 

 verse folds, like those of leather. From the mouth of 

 the vase projects the animal, whose form may be dis- 

 tinctly traced through the clear walls of the cell, at- 

 tached to its bottom, whence it stretches upward when 

 seeking prey, or to which it shrinks when alarmed. 



In the former condition the body resembles a much 

 elongated Vortioella, with a similar circular orifice, set 

 round with cilia. Often the animal performs its ciliary 

 vibrations within the shelter of its house, not venturing 

 to protrude beyond its rim. If carmine be mixed with 

 the water, the atoms are seen in the customary vortex, 

 and some are occasionally drawn into the cell nearly 

 half-way down its cavity, and then swiftly driven out 

 again. On a slight tap upon the table the animal 

 withdraws, and in the same moment the urn bends 

 down upon its leathery pedicle, at a point where there 



