464 THE BEGINNINGS OF LIFE. 



Vorticella embryos \ The change generally takes place 

 in specimens which are already encysted, and which 

 are lying side by side in a kind of tesselated pellicle 

 formed by closely-packed Euglenx. The early stages 

 of the transformation are precisely similar to those 

 which have been hitherto described. Decolourization 

 is gradually completed, till at last a whitish and very 

 finely-granular mass is produced, spherical in shape, 

 and enclosed within a rather thick cyst-wall. These 

 bodies vary in size according to the dimensions of the 

 EuglenjE which undergo transformation, and those which 

 I have mentioned ranged from toVo" ^^ "sw" ^"^ ^^^" 

 meter. They replace the Euglen^, so that they remain 

 as integral though metamorphosed parts of the coherent 

 tesselated layer. Very soon a vacuole makes its appear- 

 ance near the centre of the embryo, which subsequently 

 remains — disappearing only at short intervals. These 

 embryos, unlike those of Paramecium, do not rotate 

 within their cysts, and do not seem to exhibit any 

 movements until they are about to become free. In 

 what precise manner they effect their exit I have 

 never been able to ascertain, though I have several 

 times seen an embryo very shortly after its emer- 

 gence from its cyst (^). At this period they form 

 ellipsoidal masses of finely- granulated protoplasm, 

 generally containing one large vacuole, and presenting 



^ Ur. Gros also distinctly states (p. 312) that Vorticellee may arise in 

 this manner — though he makes no express statement concerning a simi- 

 lar origin for other forms. 



