. The biology of Stentor. Stentor. 290 THE BIOLOGY OF STENTOR the conditions in Weisz's experiments were not optimal. Further- more, Suzuki (1957) could find no evidence for differences in the potentiality of parts of the nucleus in Blepharisma at any stage. Above all, I was unable by similar experiments to confirm that a regular and recurring difference develops between the serial nodes of the nucleus (Tartar, 1957b). I tested five different races of coeruleus and observed not only oral regeneration but also recon- stitution of the nuclear chain from a single node and the capacity of fragment
. The biology of Stentor. Stentor. 290 THE BIOLOGY OF STENTOR the conditions in Weisz's experiments were not optimal. Further- more, Suzuki (1957) could find no evidence for differences in the potentiality of parts of the nucleus in Blepharisma at any stage. Above all, I was unable by similar experiments to confirm that a regular and recurring difference develops between the serial nodes of the nucleus (Tartar, 1957b). I tested five different races of coeruleus and observed not only oral regeneration but also recon- stitution of the nuclear chain from a single node and the capacity of fragments to reproduce indefinitely in clones. For comparison I studied Condylostomum magnum^ which is a very long ciliate with mouthparts far to one end and a uniform chain nucleus running the length of the body. If posterior nodes regularly become depotentiated, the same should be manifested in this form even more than in Stentor. It was found that even the single, terminal posterior node in many cases or at least the last four could support complete oral regeneration at any stage (Fig. 81). In stentors (where this was tested) pre-fissional and pre-reorganiza- tional fragments with only such nodes could give rise to viable lines with normal chain Fig. 81. Equivalence of macronuclear nodes in (A) Stentor coeruleus and (B) Condylostoma magnum. Tiny fragments of early dividers, carrying only a few of the most anterior or posterior nodes, are capable of regeneration and more. Evidently intranuclear differentiation is neither necessary for nor the consequence of cytoplasmic differentiation in ciliates. We can therefore return with confidence to the old dictum that any. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Tartar, Vance, 1911-. New York, Pergammon Press
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