POLARITY 



199 



polarity is intrinsic within each part, there is an interaction of some 

 sort by which heteropolarity may lead to extensive disharmonies 

 beyond the original misalignment. 



Fig. 54. Disturbances in heteropolar systems. 



A. Primordium sector of stage-4 reorganizer reversed in situ. 

 Absence of stomatogenesis associated with posterior end of anlage 

 lying now in the frontal field. The inverted patch {x) apparently 

 was gradually resorbed but no regeneration occurred during 



7-day survival. Nuclear distribution abnormal. 



B. Stage-2 regeneration primordium sector grafted hetero- 

 polar to regenerating stentor in same stage. Both anlagen were 

 resorbed; then two new ones produced the incomplete oral 

 diflferentiations shown in the second sketch as the shape became 

 grossly abnormal. Specimen is re-regenerating with single 



primordium. 



Polar conflicts may be resolved by the larger part becoming 

 dominant (Fig, 55A). A compromise may result in heteromorphosis, 

 in which a secondary polarity is responsible for the formation of 

 an extra set of feeding organelles but the lateral striping has, 

 throughout, the polarity of the major portion of the specimen so 

 that the secondary oral differentiation is of reversed asymmetry (b). 

 These forms are however less frequent and less well-developed in 

 Stentor than in other ciliates. When the major mid-section of the 

 cell is reversed, all parts retain their original polarities and 

 multiple formations occur (C). 



Shifting the head to the posterior end does not result in reversal 

 of polarity. The most frequent result (unpublished) was that a new 

 set of feeding organelles eventually regenerated at the original 

 anterior end of the major cell body, and the displaced head became 



