INFUSORIA ENCYSTING PROCESS. 



419 



272. TheTecent observations of Stein and other Microscopists 

 have drawn attention to another very curious mode of propaga- 

 tion, the phenomena of which were completely misapprehended 

 by Prof Ehrenberg. Many Infusoria at certain times undergo 

 an encysting process ; that is, their body secretes from its surface 

 a sort of gelatinous case, which hardens so as completely to 

 enclose it, the Animalcule, however, still remaining free in the 

 interior of its coffin-like investment. Previously to the forma- 

 tion of this cyst, the Animalcule loses its activity, its form 

 becomes more rounded, and its cilia or other filamentous pro- 

 longations are lost or re- 

 tracted, as is well seen in FlG - 198 - 

 Vorticella (Fig. 198, A); 

 and it was not, perhaps, 

 very unnatural, that the 

 encysting process should 

 have been considered by 

 Prof. Ehrenberg as the 

 expiring effort of life. If 

 the cysts and their con- 

 tents, however, be atten- 

 tively watched, it will be 

 seen that the process is 

 preliminary to a produc- 

 tion of new individuals ; 

 and this may take place 

 in different modes. For 

 sometimes the substance 

 of the body appears to 

 break up (c, D)into nume- 

 rous "gemmules," which 

 are analogous to the 

 " zoospores" of Proto- 

 phytes, and which, like 

 them, are set free by the 

 bursting of the parent 



Cell(E), Swimming forth tO Development and Metamorphosis of Vorticella microstoma: 

 into A ' f u ""g row " individual in its encysted state; a, retracted 

 oval circlet of cilia; 6, nucleus; c, contractile vesicle; B, 

 a cyst separated from its stalk ; c,the same more advanced, 

 Same kind though at first t ^ ie nuc ' eus broken up into spore-like globules; D, the same 



more developed, the original body of the Vorticella, d, having 



tearing nO re- Become sacculated, and containing many clear spaces; B, 



Semblance tO the type Of oneofthesacculations having burst through the enveloping 



their DredeceSSOr In CySt ' a elatinou8 mass > containing the spores, is dis- 



. P charged; F. transformation of encysted Vorticella (B) into 



Other instances, however, form of Acmeta; b, nucleus; G, stalked Acineta form of 



Onlv a sinS"! e offsDrinS* is Vorticella, enclosing a young one, the result of the transfor- 



,P .,* mation of the nucleus; H, young free Vorticella; a, b, c, as 



developed from the " nu- in Flg . i ; 0t posier[or circlet of ciiia. 

 cleus" of the original cell- 

 body, which offspring may have an entirely dissimilar form ; and 

 this latter change occurs in Vorticella, in conjunction with other 



HOW individuals OI the 



