io6 



THE BIOLOGY OF STENTOR 



Fig. 24. Stages in oral regeneration following excision of feeding 

 organelles (S. coeruleus.) 



Stage I. Anterior end healed over and primordium appears 

 as a rift across fine striping near area of widest stripes. (Omitted 

 stages correspond to those in the development of the oral anlage 

 in division — see Fig. 14.) 



Stage 5. Primordium with expansion at posterior end where 

 mouthparts will form. Multiplication of fine stripes within the 

 arc of the anlage which will form the new frontal field. 

 Macronu clear nodes coalescing. 



Stage 6. Invagination of the end of the primordium to form 



cytostome and gullet. Nucleus compacted, but usually not as 



much as in division. Stripe multiplication below anlage will 



form a new fine-line zone and recover approximately the normal 



number of lateral stripes. 



Stage 7. Gullet and cytostome now well formed and oral 

 pouch invaginating as primordium moves to anterior end. 

 Macronucleus renodulating. (After Tartar, 1957c.) 



