362 THE BIOLOGY OF STENTOR 



Blepharisma is also a heterotrichous ciliate, with bands of (red) 

 pigment granules lying between the kineties or rows of body cilia. 

 Otherwise stentors and blepharismas are notably different in 

 general aspect. Blepharisma is scarcely or not at all contractile, has 

 no holdfast, possesses a terminal contractile vacuole and cytopyge, 

 and has an undulating membrane to the right of the mouthparts, 

 paralleHng the peristome or row of membranellar plates. There is 

 no obvious gradation in pigment stripe widths around the cell, but 

 posterior to the mouth lies a ramifying zone where the kineties 

 bifurcate in multiplying, especially during the earliest stages of 

 division. Suzuki's drawing indicates that multiplication of clear 

 stripes begins in the left anterior corner of this V-area, just as in 

 Stentor. This region is also the site of oral primordium formation. 

 A groove or rift in the ectoplasm there occurs, and anlagen 

 development shows only two points of difference: first, the pri- 

 mordium separates longitudinally to place the undulating mem- 

 brane on one side of an oral groove and the membranellar band on 

 the other; and second, the anlage is apparently always parallel to 

 the lateral striping instead of at first cutting across the stripes. This 

 is understandable because Blepharisma has no frontal field and 

 lateral striping therefore does not need to be shifted forward. The 

 feeding organelles remain deployed longitudinally on one side of 

 the cell, extending from the anterior pole to about mid-body level 

 instead of being shifted entirely to the anterior end. 



Major points of similarity are as follows. In division, the fission 

 line is seen as a clear band from which pigment granules are 

 missing, as in Stentor, and its position is determined late in the 

 division cycle. Indifferent ectoplasm blocks the division furrow. 

 Injury apparently causes the resorption of early division primordia, 

 but mid-stage dividers complete division after excision of the 

 original feeding organelles ; and if the division furrow is destroyed 

 a divider is converted into a reorganizer. The macronucleus does 

 not necessarily split into two equal parts, for in cut dividing cells a 

 smaller amount is received by smaller than normal daughter cells. 

 After mid-stage, division is completed even in the absence of the 

 nucleus or of the division primordium. If only the nucleus is 

 excised, completion of the opisthe shows that primordia, in what 

 probably correspond to stage 5 of Stentor, can complete the oral 

 differentiation. Removal of a substantial part of the membranellar 



