ACTIVATION AND INHIBITION I ORAL PRIMORDIUM 153 



regeneration and division are very similar. In both, the macro- 

 nuclear beads coalesce. Causin even described an instance of 

 temporary division of this compacted nucleus in a regenerating 

 stentor, though this is probably exceptional. In both there is 

 mitotic division of the micronuclei (Guttes and Guttes, 1959). 



Reorganization is obviously similar to regeneration in that a new 

 set of feeding organelles is produced while the original individuality 

 of the organism is retained, and the accompanying nuclear changes 

 are similar. Schwartz (1935) commented on the resemblances 

 between reorganizers and dividers: in both there is oral primor- 

 dium formation in the presence of an already complete set of 

 feeding organelles; and in reorganizers as in dividers there can 

 occur the mitotic multiplication of micronuclei as well as an 

 increase in the number of macronuclear nodes. A basic similarity 

 in division, reorganization, and regeneration was recognized by 

 Weisz (1949a) who conceived of these processes as alternative 

 responses to a graded series of stimuli increasingly forceful in 

 their extrinsic character. 



In all three programs of morphogenesis, oral primordium 

 formation occurs and a basic similarity is best demonstrated by 

 the fact that the anlage can be rerouted to serve other ends than 

 that for which it was originally "intended". In other words, 

 morphogenesis can be Preprogrammed"; for it can be shown 

 that a stentor is not irrevocably set upon one course from the start. 

 Johnson, for example, described a case in which a reorganizing 

 coerideiis seemed to have transformed itself into a divider. At first 

 the primordium ran all the way forward to contact the original 

 membranellar band, as is characteristic of reorganizers, but then 

 a secondary contractile vacuole developed and the anterior portion 

 of the anlage was resorbed, whereupon the cell divided. I read this 

 report with some scepticism because I have never seen resorption 

 restricted to one section of the primordium; although I have 

 observed three instances in which a coeruleiis which should have re- 

 organized divided instead. These were from regenerating animals, 

 the primordium and neighboring Ectoplasm and endoplasm of 

 which had been excised so that they had already suffered a con- 

 siderable reduction in volume, which is supposed to preclude 

 division (Weisz, 1956). A new anlage was then produced so 

 rapidly that no stripe multiplication occurred and the resulting 



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