Fission after division primordium removal in the ciliate Stentor coeruleus and comparable experiments on reorganizers

Abstract

1. 1. Following excision of division primordia even at the earliest stages, stentors can go on to complete nuclear and cytoplasmic division without the normally concomitant development of this oral primordium. 2. 2. The majority of the dividers did not replace the excised primordium by formation of a new one. 3. 3. Reorganizers are like dividers in also continuing on this course after primordium excision, resorbing the old mouth although no new one is ready to take its place, and in not renewing the oral primordium in the majority of cases. 4. 4. Regenerators, in contrast, promptly replace the excised oral primordium by formation of a new one, as here confirmed. The relevance of these findings to the problem of cell division in ciliates and to the interpretation of the reorganization process is indicated.