284 THE BIOLOGY OF STENTOR 



nuclear chains this condition is corrected after clumping and 

 renodulation in division. Stolte also made much of divergence from 

 the normal picture w^ith regard to the nucleus which occurs in 

 highly vacuolated stentors. But in pathological material one cannot 

 be sure that the vacuoles push the nuclear nodes out of place, 

 since the necrotic condition could affect the nucleus directly. 

 Certainly the vacuoles do not push the nucleus to the periphery 

 of the cell, as he said, because it is there already. 



In regard to the second qualification — that the nucleus need not 

 be at a special place — v^e have the evidence that in stentors in 

 which all but one nuclear node has been removed this bead may 

 be variously located, yet such animals can survive and regenerate. 

 Still more satisfactory tests could easily be devised by shifting the 

 whole nucleus in such a way that it could not soon recover the 

 normal location, and it would be especially interesting to determine 

 whether the nucleus, separated by a narrow neck of cytoplasm from 

 the major portion of the cell, could support regeneration and growth 

 by diffusions across this bridge. 



Certain regular changes in the distribution of the nucleus may 

 now be noted. When the posterior end of coeruleiis was cut off in 

 mid-fission it was consistently found that after renodulation the 

 nucleus in the opisthe had at first an abnormal arrangement, but 

 the typical disposition was later achieved (Fig. 78c). When graft 

 complexes become persisting doublets the nuclear chain is dupli- 

 cated even though the specimen started with but one (d), and when 

 doublets transform back into singles they soon achieve a normal, 

 single chain (e). In Fig. 59c we have a stentor developing a 

 secondary tail-pole which later became furnished with an extension 

 of the nuclear chain. 



Similar deviations in the location of the nucleus in abnormal 

 forms have been observed in the related genus Condylostoma 

 (Yagiu, 1951, 1952). The simplest explanation of these cases would 

 be that the stripe pattern guides the location of the macronuclear 

 nodes. And the best substantiation thereof is that in cases of 

 reversed asymmetry, with the same cell shape as in normal animals, 

 the macronucleus assumes a reversed location (see Fig. 49). 



2. Clumping of the nucleus 



Typically, all nodes of the moniliform nucleus lie within a single 



