Stomatogenesis in Resting Cysts of Colpodidae

SYNOPSIS. The reorganization in resting cysts which produce a single emerging individual was followed in 5 species of Colpodidae forming a possible evolutionary series with increasing numbers of kineties. Stomatogenesis in Colpoda maupasi and C. inflata was studied for the first time; that in C. steinii, C. cucullus and Tillina magna was reinvestigated with new observations. In all, the oral primordium is double and originates from segments of certain somatic kineties, constant for each species. The larger mouthparts in the larger ciliates are produced from a correspondingly greater number of kineties. Morphogenetic and evolutionary implications of this series of observations are discussed.