3i8 



THE BIOLOGY OF STENTOR 



B 



Fig. 91. Effects of niger graft on coeruleus. 



A. Regeneration blocked, no bleaching of coeruleus — the 

 usual result, a: Enucleate niger grafted and mouthparts of 

 coeruleus excised, b: Yellow niger pigment disappears but not 

 the coeruleus coloration, c: In spite of regression of niger graft 

 no primordium formation occurs and macronucleus becomes of 



5 large nodes. 



B. Unusual response to same type of graft, a: Regeneration 

 occurs, with a secondary primordium forming in suture between 

 fine niger stripes and broad striping of host, b: Only the host 

 anlage has complete stomatogenesis. c: re-regeneration follows 

 with still less development of the primordium associated with 

 niger graft. Host nucleus abnormal, with few and unequal nodes, 

 two of which migrated to lie underneath the graft. (After 



Tartar, 1956c.) 



in character halfway between those of the two species. In some 

 combinations differentiation occurred but the cooperation of the 

 two nuclei was defective and abnormal structures resulted, as in 

 the case without membranelles in Stentor. 



On the whole this behavior is quite different from the situation 

 in Stentor, although the comparison is limited by the fact that 

 all stentors produce the same form of oral differentiation. In Stentor 

 the cytoplasms seem to be much more specific and nuclei are 



