32 POPULAR ILLCTSTKATIONS OF 



upon which it pleases Vorticella to feed. But strange, yet true, this 

 mouth exercises a power of selection, and, by the assistance of small 

 non-vibratile cilia which pass through the mouth into the gullet, it 

 rejects all non-nutritious particles, and chooses soft eatable animal- 

 cules only. The food goes into the gullet, and, after remaining at 

 the bottom thereof for some time, it passes into the general cavity 

 through an opening at e. The nutritious parts are now dissolved in 

 the juices of the body, and the rest sent out by the same opening 

 through which it found admittance. 



The contractile vesicle, nucleus, and nucleolus are shown, but the 

 changes in them are similar to those described in Paramaecium. 

 Now this animalcule may increase by fission ; now and then, but 

 not often, a bud grows out at the bottom of the cup, which is 

 developed into a perfect bell, and being provided with posterior 

 cilia, like d (Fig. 27, p. 30), goes through the same processes of 

 development which I have just described. 



Fig. 29. Fig. 30. 



Fig. 29. Vorticella encysted on its stalk. 



Fig. 30. Acineta stage of Opercularia articulata (one of the Vorticellinoe) a, dendritic 

 nucleus - 6, cyst c, tentacles d, enlarged stalk. 



Strange as are these undoubted facts, there is one mode of repro- 

 duction stranger still. Instead of conjugating, dividing, or budding, 

 our Vorticella may adopt a still more complicated means of repro- 

 ducing its kind. It draws in its disc, as noticed above, and the 

 peristome contracting the bell becomes of an oval shape. It now 

 envelopes itself in a cyst, as we saw the Gregarinee do, which cyst is 

 a mere secretion from the sarcode body. It has now the appearance 

 shown in Fig. 29. It then pushes out tentacular appendages, the 

 stalk thickens, and it looks for all the world like a gutta-percha 

 elastic bottle, as shown in Fig. 30. No wonder that its best friends 



