420 



MICROSCOPIC FORMS OF ANIMAL LIFE. 



peculiarities of a very remarkable kind. For the encysted Vor- 

 ticella becomes changed into the form of an Acineta (closely re- 

 sembling that of Actinophrys), as shown in Fig. 198, F; and this 

 may acquire a new stalk, so as to correspond with a Podophrya 

 (G). At the same time, its band-like nucleus becomes entirely 

 metamorphosed into a free body of ovate form, which carries at 

 its narrower end a circlet of long vibrating cilia, while its more 

 obtuse end is perforated by a mouth which communicates with 

 a distinct oral cavity. In the interior of this offspring (H), we 

 already observe a long oval nucleus (b) and a round contractile 

 vesicle (<?), and its whole aspect is that of a young Yorticella-bud 

 just ready to quit its stock. This body escapes from the interior 

 of the Acineta by a gap formed in some part of its wall, which, 

 however, soon closes again, and the Acineta goes on stretching 

 out and retracting its radiating filaments, and after a time pro- 

 duces in its interior a new nucleus for a second Vorticella-bud. 1 

 273. Another interesting series of phenomena, of the same 

 order, is presented in the development of the Animalcule desig- 

 nated by Muller as TricJioda tynceus, which has been carefully 

 studied by M. Jules Haime. 2 The form which seems most pro- 



FIG. 199. 



Metamorphoses of Trichoda lynceus : A, larva (Oxytricha) ; B, a similar larva, after swallowing the 

 animalcule represented at M; c, a very large individual on the point of undergoing fission ; D, another 

 in which the process has advanced further; E, one of the products of such fission; F, the same body 

 become spherical and motionless; G, aspect of this sphere fifteen days afterwards; H, later condition 

 of the same, showing the formation of the cyst; I, incipient separation between living substance and 

 exuvial matter; K, partial discharge of the latter, with flattening of the sphere ; L, more distinct for- 

 mation of the confined animal; M, its escape from the cyst; N, its appearance some days afterwards : 

 o, more advanced stage of the same ; p, Q, perfect individuals, one as seen sideways, moving on its 

 bristles, the other as seen from below ; these are magnified twice as much as the preceding figures. 



perly to be considered as the larval one, is that shown in Fig. 

 199, A-E, which has been described by Prof. Ehrenberg under 



1 See Prof. Stein's Memoir in " Siebold and Kolliker's Zeitschrift," Bd. iii, and the 

 translation of it in " Ann. of Nat. Hist." 2d Ser. vol. ix, p. 471. 



2 Annales des Sci. Nat." Se"r. 3, torn, xix, p. 109. 



