458 EVENINGS AT THE MICROSCOPE 



while, soon heals its wound, and after a while develops a 

 new nucleus, which passes through the same stages as I 

 have described, and bursts out a second Vorticella. 



But the cycle .of changes may be quite different from 

 this. For sometimes the nucleus within the Acineta, in- 

 stead of forming a Vorticella^ breaks itself up into a great 

 number of tiny clear bodies, resembling Monads, which 

 soon acquire independent motion, and glide rapidly about 

 the cell formed by the enclosed Vorticella-loody as in a 

 little sea. But by and by this body, together with the 

 Acineta wall, suddenly bursts, and the whole group of 

 Monad-like embryos are shot out, to the number of thirty 

 or upward. 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 become 

 fixed, develop stalks, which are at first not contractile, 

 and gradually grow into perfect Vorticellce, small at the 

 beginning, but capable of self-division, and of passing 

 into the Acineta stage, and gradually attaining the full 

 size of the race. 



Some forms of the same family, Vorticelladce, are inter- 

 esting as dwelling in beautiful crystalline houses, of vari- 

 ous shapes, always elegant. All these have been ascer- 

 tained to pass through the same or similar Acineta stages. 

 Cothurnia imberbis is one of the prettiest of these. The 

 cell is of an elegant ampulla-like form, perfectly transpar- 

 ent and colorless, set on a stiff foot, or short pedicle, 

 which shows many transverse folds, like those of leather. 

 From the mouth of the vase projects the animal, whose 

 form may be distinctly traced through the clear walls of 

 the cell, attached to its bottom, whence it stretches up- 



