. The biology of Stentor. Stentor. Fig. 43. Oral induction associated with the posterior pole. A. Stage-2 primordium of regenerator shifted to the anterior pole develops no mouthparts but only membranellar band. B. Stage-3 regeneration primordium implanted heteropolar on a stage-3 regenerator. Primordium patch slips to posterior end where it forms good mouthparts and an extra oral pouch (y) and gullet (x) in addition. 4. Induction of mouthparts formation As just indicated, there is accumulating evidence that the posterior end of the cell in Stentor has an inductive action on the end of the dev
. The biology of Stentor. Stentor. Fig. 43. Oral induction associated with the posterior pole. A. Stage-2 primordium of regenerator shifted to the anterior pole develops no mouthparts but only membranellar band. B. Stage-3 regeneration primordium implanted heteropolar on a stage-3 regenerator. Primordium patch slips to posterior end where it forms good mouthparts and an extra oral pouch (y) and gullet (x) in addition. 4. Induction of mouthparts formation As just indicated, there is accumulating evidence that the posterior end of the cell in Stentor has an inductive action on the end of the developing membranellar band which causes it to invaginate and form mouthparts. Perhaps the first indication of this relationship was in experiments in which a sector bearing the primordium site was reversed in situ and the original mouthparts excised to initiate regeneration (Tartar, 1956b). An oral primor- dium then appeared in the reversed patch but mouthparts now were formed at both ends (Fig. 44A). Formation of the normal mouthparts at the original posterior end of the anlage may be regarded as due to the influence of its own surroundings of "posterior" ectoplasm, and that of the additional formation at the other end as being produced by an influence of the adjacent tail- pole, passing across the graft and affecting the originally anterior end of the anlage. This experiment has been confirmed by Uhlig. 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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