CILIATES 185 



entire organisms, flows into the suctorian's body; or both 

 functions may be performed by the same tentacles. Asexual 

 reproduction is by internal or external budding of ciliated larvae 

 which swim away and shortly metamorphose into sessile, non- 

 ciliated adults. Kinetosomes, scattered or in groups, are present 

 in the adult. 



Suctorians present at least two problems of broad general 

 interest. One is the morphological basis of tentacle action : by 

 what means are prey organisms held and immobilized, and how is 

 their cytoplasm moved into the predator's body ? The second is 

 the morphogenesis of the ciliated larva, and in turn of the ten- 

 tacled adult. A limited amount of electron-microscope data 

 bearing on these problems is available. Observations on dried 

 whole tentacles by Blanc-Brude, Dragesco, and Hermet (1951) and 

 by Rudzinska and Porter (1954a) provided suggestive preliminary 

 information, augmented by Rouiller, Faure-Fremiet, and Gauchery 

 (1956b) from detailed examination of thin sections of the two 

 types of tentacles of Ephelota plana. A continuing study of 

 Tokophrya infusionum by Rudzinska and Porter (1955) has led to 

 thorough accounts of macronucleus and contractile vacuole 

 ultrastructure, already discussed in Chapter 2, but their other 

 data, scattered through several unillustrated notes, have yet to 

 be assembled in a documented report. An abstract by Pottage 

 (1959) deals with aspects of morphogenesis in Discophry a piriformis. 



In Ephelota, the cytoplasm of the adult cell body is limited by a 

 thick (to 04/x), smooth, homogeneous layer called the epi- 

 plasmic membrane, overlain by an alveolar cuticle consisting of 

 packed spheroidal vesicles of various sizes. The epiplasm is shown 

 by light microscopy to be protein, while the cuticle appears to be 

 predominantly mucopolysaccharide. Fibrous cylinders identifi- 

 able as resting kinetosomes are seen erratically, embedded in the 

 epiplasmic membrane, perpendicular to its surface. Over the 

 tentacles the alveolar layer continues without interruption and 

 the epiplasmic membrane narrows to form a thin pellicle, some- 

 times convoluted. The sucking tentacles are extensile and 

 contractile ; they average 3^ in total diameter. Within the 

 epiplasmic membrane a cortex of cytoplasm surrounds a layer of 

 close-set, longitudinal, tubular fibrils, about 20 m/x in diameter. 

 From this layer 26 to 28 radially disposed crests or lamellae, 



