Ciliophora 415 



50, C, E) which extends into the endoplasm for a short distance. The 

 tentacles adhere to a suitable ciliate which comes in contact with them 

 and are powerful enough to hold prey much larger than the captor (Fig. 

 7. 50, H, I). Prompt paralysis of the captured organism has often been 

 reported. Shortly after contact, protoplasm of the prey starts flowing down 

 the tentacle to the base of the tube, where food vacuoles are formed. 

 Whether the pellicle of the prey is ruptmed by suction or undergoes lysis 

 upon contact with the tentacle is uncertain. Ingestion is rapid. Tokophrya 

 le.jnnoriim, for instance, ingests Eiiplotes patella in about fifteen minutes 

 (156). 



The flow of material through the tentacle during feeding suggests the 

 exertion of suction, the source of which has remained an intriguing prob- 

 lem. Perhaps it is significant that activity of the contractile vacuole is 

 increased about five-fold in Tokoplirya infusionum as the organism begins 

 to feed (184). Dragesco and Guilcher (53) have noted, by means of phase- 

 contrast microscopy, that the wall of the inner canal may undergo con- 

 tractions suggesting a sort of peristaltic activity. Whether such activity 

 plays a major part in ingestion is not yet certain. 



The suctorian stalk, present in many species, is always non-contractile 

 although not necessarily homogeneous in structure (156). The upper end 

 of the stalk may be expanded as a small cup in which the base of the 

 body rests, or in other cases, the distal end of the stalk fits into a depres- 

 sion in the body (Fig. 7. 50, G). In the metamorphosis of ciliated larvae, 

 the stalk apparently arises from an organelle analogous to the scopula 

 of Peritrichida (Fig. 7. 51, L). 



Some of the Suctorea are equipped with a secreted lorica which is often 

 open distally, leaving the apical end of the body free (Fig. 7. 56, A), or 

 may be a fairly heavy wall enclosing the body as in Squalophrya macro- 

 styla (Fig. 7. 53, H, I). 



The relationships of the Suctorea to ciliates are indicated in the life- 

 cycles of most species. Reproduction typically involves budding, either 

 internal (Fig. 7. 51, N-P) or external. Although it appears to be unusual, 

 both internal and external budding may occur within a single species, as 

 reported for Anarma inultiriiga (80). The bud usually develops into a 

 ciliated larva (Fig. 7. 51, A-K), which after a short period of swimming, 

 undergoes metamorphosis. After the larval stage of Tokophrya lemnarum 

 becomes attached (Fig. 7. 51, L, M), a stalk is secreted within a few min- 

 utes, the tentacles have grown to normal length about fifteen minutes 

 after they are first detectable, and the adult form is fully developed within 

 an hour (156). Even more rapid metamorphosis has been noted in 

 Tokophrya infusionum (185). 



The disappearance of cilia during metamorphosis apparently does not 

 include their basal granules, which persist in the adult stage of Podophrya 

 fixa (32). In reproduction, the bud receives some of the parental basal 



