292 



THE BIOLOGY OF STENTOR 



cytoplasmic volume (Allescher, 19 12), or animals regenerated from 

 fragments with proportionately too much nucleus, tend at first 

 and for a long time merely to decrease the surface of the nucleus by 

 fusion of nodes (Fig. 82B). Nor did Hartmann (1928) observe 

 decrease in size of the nucleus in successive excisions of amoeba 

 cytoplasm. Yet indubitable decrease in nuclear volume eventually 

 occurs in hypernucleated Stentor fragments, as Prowazek (1904) 

 first reported. Stentors therefore certainly tend by nuclear increase 

 or decrease toward a nucleo-cytoplasmic ratio of limited range. 



A 



Fig. 82. Size adaptations of macronucleus in S. coeruleus. 



A. Stentor with only 6 nodes, half of which are much 

 attenuated, as if to compensate with added surface and to make 

 a typically disposed nuclear chain. Mouth was excised and after 

 coalescence during regeneration 12 nodes were formed, normal 



in shape, but in forked arrangement in this case. 



B. Nucleate portion with 14 nodes is excised, regenerates 

 proportionate feeding organelles and reduces the number but 



not the size of the nodes. 



Size of nuclear beads in the row is generally quite uniform, with 

 the exception of interpolated nodes which are, at least initially, 

 very small. Daughter cells have approximately the same number 



