The Somatic and Oral Infraciliature of the Enigmatic Giliate Cyathodinium piriforme*

Abstract

SYNOPSIS. The unusual patterns of infraciliary kinetosomes on the body and in the large anterior depression of the trophont stage of this difficult‐to‐classify ciliate have been examined by use of the Chatton‐Lwoff silver impregnation technique. In our material there are nine rows of somatic cilia, arranged more or less concentrically around the oral cavity at the anterior end of the pyriform‐shaped body; in the cavity itself there are eight quite separate rows of “vestibular” ciliature. Erratically distributed on posterior areas of the body are argentophilic “granules” which may be non‐cilia‐bearing kinetosomes. A contractile vacuole pore, described for the first time, is located on the ventral surface in the posterior third of the body to the right of the midline. Still more information is needed to be able to establish the most appropriate taxonomic allocation for Cyathodinium. It is suggested that a combination of fine structural (electron microscopical) and morphogenetic (fission, stomatogenesis, reorganization) studies is required to elucidate both the form and the function of the several unique features of Cyathodinium and that a new understanding of these will permit resolution of the problem of the systematic status of the ciliate.

Endogenous Bud Formation in Histriculus vorax, a New Asexual Reproductive Process In the Hypotrichida

“…I t is a general rule that, when the ciliature is suppressed in an adult ciliate, free or 'erratic' kinetosomes persist, and it is these which supply the cilia for the larval phase. Suppression of ciliature and presence of 'erratic' kinetosomes have been reported in a variety of groups: in Suctorida(4, l O , l l ) , in Chonotrichida(l2), in Hypotrichida(S), and possibly in the enigmatic ciliate Cyathodinium ( 16). In the adult stages, the 'erratic' kinetosomes are scattered a t random below the pellicle, and in the first 2 examples cited above they form a local concentration in preparation for budding, divide, and assume an orderly arrangement that is transmitted to the bud.…”