92 



as 



THE BIOLOGY OF STENTOR 



any free nodes forward to a position directly under the 

 developing primordium and he claimed that this is a precise and 

 invariant event in reorganization, though neither Schwartz nor I 

 confirm this. Essentially, the macronucleus clumps and renodulates 

 without dividing. 



b ^ c ^ d 



Fig. 20. Course of reorganization (S. coeruleus). 



a: Morphologically complete animal shown with stage-3 

 primordium. b: Stage-4 anlage intirriately joining with original 

 membranellar band, c: During stage-6 of primordium develop- 

 ment the old band between joining point and mouthparts, 

 together with those parts, is resorbed. d: New mouthparts 

 and addition to membranellar band moving into place and 

 carrying new fine stripes into the frontal field which now shows 

 a double pattern, 2 swirls. 



Since the granular carbohydrate reserves in the posterior end 

 of the cell undergo remarkable shifts in division, their behavior 

 during reorganization should be noted. Weisz reported that the 

 granules remained in place without change, but I observed that 

 generally they diffuse forward under the ectoplasm though not 

 separating into two groups (Tartar, 1959a). The chief resemblance 

 between reorganizers and dividers is that in both cases a primor- 

 dium is formed although feeding organelles are already present. 

 In the tendency of the carbohydrate reserves to migrate there is 

 also a slight similarity, but points of distinct difference are that 

 no second contractile vacuole is formed during reorganization 

 (Johnson, 1893) and of course no fission line. 



The anterior end of the anlage now fuses with the original 

 membranellar band, often causing a slight deflection where it 

 joins ; and the section of the old band between this juncture and 

 the mouthparts then dedifferentiates and is resorbed along with 

 the last traces of the gullet. The original oral pouch apparently is 



