. The biology of Stentor. Stentor. REGENERATION 127 plasmic striping grew out and the normal form and proportions of a stentor were reconstituted on a small scale. But nothing of this happened if no nuclear beads were included and the fragment then remained until death about four days later just as it was after cutting and healing. It would therefore seem that the nucleus is essential in both the formation and the dedifferentiation of oral structures. These cases demonstrate how capable is Stentor in adjusting its parts to normal Fig. 32. Adjustment of size of parts in nucleated,
. The biology of Stentor. Stentor. REGENERATION 127 plasmic striping grew out and the normal form and proportions of a stentor were reconstituted on a small scale. But nothing of this happened if no nuclear beads were included and the fragment then remained until death about four days later just as it was after cutting and healing. It would therefore seem that the nucleus is essential in both the formation and the dedifferentiation of oral structures. These cases demonstrate how capable is Stentor in adjusting its parts to normal Fig. 32. Adjustment of size of parts in nucleated, isolated head of S. coeruleus. Feeding organelles and frontal field are excised without injury but with minimum lateral ectoplasm. In folding to cover the wound the fragment becomes much contorted. Membranellar band decreases in length and lateral striping gradually grows out to form a tail-pole. Later the mouthparts are also decreased in proportion. Adjustment occurs without primordium formation but only if nucleus is present. 7. Can mouthparts and membranelles be formed in situ ? In the normal course of life new feeding organelles in Stentor are formed only through the development of an oral primordium; yet there are hints in the literature that this may not be the only pathway to oral differentiation, although no really convincing demonstrations have been offered. In respect to the mouthparts, D. Primordium sector isolated from a stage-4 regenerator. Development continues and size of mouthparts is proportionate not to the original cell or the length of the anlage but to the size of the fragment. E. Tail pole was grafted to frontal field of a stage-2 regenera- tor. First sketch shows an additional anlage now induced in the graft. On developing, the primordia produced mouthparts proportionate to the size of the part in which they Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and
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