PROTOZOA : INFUSORIA. 69 



bulum " into a fusiform canal or " pharynx," which terminates 

 abruptly in the abdominal cavity. The particles of food are 

 taken in at the mouth, descend through the short alimentary 

 canal, and enter the abdominal cavity where they are subjected 

 to the general rotation of the "chyme-mass," being finally 

 excreted by an anal aperture which is situated near the mouth. 

 As in Paramozcitim, the body in Vorticella is composed of an 

 outer " cuticle," a central " chyme-mass," and an intermediate 

 "cortical layer," which contains a contractile vesicle and a 

 band-like nucleus. 



Reproduction in Vorticella may take place by fission, or by 

 gemmation, or by a process of encystation and endogenous 

 division. In the first of these modes the calyx becomes in- 

 dented in a longitudinal direction viz., from the pedicle to the 

 disc; and the groove thus formed becomes gradually deeper 

 until the calyx is finally divided into two halves supported 

 upon the same pedicle. On one of these cups a "pos- 

 terior" circlet of cilia is then formed in addition to the 

 "anterior" circlet already existing (i.e., a fringe of cilia is 

 developed round that end of the calyx which is nearest the 

 attachment of the pedicle and furthest from the disc). The 

 cup (fig. n, d\ thus furnished with a circlet of cilia at both 

 extremities, is then detached, and swims about freely. Finally, 

 the anterior circlet of cilia disappears, and this end of the 

 calyx puts forth a pedicle and becomes attached to some 

 foreign object. A new mouth is now formed within what 

 was before the posterior circlet of cilia ; so that the position 

 and function of the two extremities of the calyx are thus 

 reversed. 



In the second mode of reproduction, namely that by gem- 

 mation, exactly the same phenomena take place, with this 

 single difference, that in this rase the new individual is not 

 produced by a splitting into two of the adult calyx, but by 

 means of a bud thrown out from near its proximal extremity. 

 This bud is composed of a prolongation of the cuticular and 

 cortical layers of the adult with a caecal diverticulum of the 

 abdominal cavity or chyme-mass. It soon develops a posterior 

 circlet of cilia, the connection with the parent is rapidly con- 

 stricted until complete separation is effected, and then the 

 process differs in no respect from that described as occurring 

 in the fissiparous method of reproduction. 



In the third mode of reproduction the Vorticella encysts 

 itself in a capsule, the cilia and pedicle disappear, and the 

 nucleus breaks up into a number of rounded germs which are 

 ultimately liberated by the rupture of the cyst, and, after a 



