48 INFUSORIA. 



The Vorticellian thus encased becomes attenuated and folded upon 

 itself ; the sarcodic substance appears to traverse its integument in all 

 parts ; from time to time it still contracts, but ultimately becomes com- 

 pletely dissolved, so that we find in its place merely a homogeneous 

 sarcodic liquid, containing granules, together with the nucleus, which 

 resists the general destruction. In the sarcode there takes place a pro- 

 cess which may be in some measure compared with what occurs in the 

 vitellus after the fecundation of an ovum. The granules becoming 

 united together form groups, which soon divide and subdivide ; at the 

 same time an integument is formed upon the surface, which is con- 

 tractile, covered with vibratile cilia, and closed at all points. The cyst 

 now contains a new Infusorium, which may be compared with the 

 Opalince or Bursarice which are met with in the intestines of the Ba- 

 trachians. 



(102.) The next part of the process is the transformation of the 

 ciliated Infusorium thus obtained into an Acineta. While the meta- 

 morphosed Vorticellian revolves in the interior of the cyst, it undergoes 

 development, increases in size, and its whole surface becomes covered 

 with folds : at length a moment arrives when the cyst, yielding to the 

 pressure exerted in its interior, bursts ; the ciliated Infusorium becomes 

 free, and swims about with a rotatory movement, and is gradually de- 

 veloped into an Acineta. Fourthly, ciliated embryos make their ap- 

 pearance in the interior of the Acineta thus produced, apparently 

 formed at the expense of the nucleus ; the nucleus becomes totally 

 converted into an embryo, and after the expulsion of the latter a new 

 nucleus is formed, which in its turn becomes transformed into another 

 embryo, and so on. Lastly, the embryos become fixed, and transformed 

 into young Vorticellce. 



According to Stein, therefore, the Vorticellce by this process of en- 

 cysting are transformed into Acinetae, and these again, by means of 

 internal motile embryos which are emitted from them, change into 

 Yorticellse. But the reality of this metamorphosis has been disputed 

 by several careful observers ; nevertheless Professor Stein still retains 

 his original views upon this subject*. 



(103.) The encapsulation of Kerona pustulata is thus described by 

 Mr. Carter : " The first change that occurred was the absence of all 

 crude aliment in the abdominal cavity ; then a division of the nucleus 

 into four parts, preparatory to its disappearing altogether. At the same 

 time certain dark angular grains, which had been floating round with 

 the sarcode of the abdominal cavity, became congregated in the poste- 

 rior extremity. The Kerona now became shortened, its cilia disappeared, 

 and finally it passed into a rounded-oval ball. This, after a certain 



* Vide an elaborate paper by Dr. H. Cienkowski, in the ' Bulletin de la Classe 

 Physico-Mathematique de 1'Acad. Imp.des Sciences de St. Petersbourg' for January 

 1855. 



