184 THE BIOLOGY OF STENTOR 



immediately taking place between the materials of the " last " 

 fine stripe and the ** first " wide stripe. In certain graft combina- 

 tions one obtains what may be called the locus of stripe contrast 

 in the strict sense of the term. For instance when the anterior half 

 is rotated on the posterior, wide stripes abut fine stripes but 

 careful examination shows that wide and narrow bands do not fuse 

 together even though they are homopolar, and this may also be 

 true of the associated ciliary rows. In heteropolar telobiotics (e) it 

 is even more obvious and probable that joining does not occur, as 

 a definite suture persists. When patches are grafted parabiotically 

 but in reverse orientation, the fact that they usually retain their 

 original polarities and slip on or creep away from each other, is 

 indicative that heteropolarity of adjacent striping prevents the 

 most intimate structural union, although the line of heal may 

 appear quite perfect. Now, in such cases the anlage seems to 

 appear within the suture and therefore at an l.s.c. in the strict 

 sense rather than in the sense of mere adjacency, as in the normal 

 primordium site. In either type of formation it is clear that there 

 is something about the juxtaposition of wide- with narrow-stripe 

 areas which locates primordium formation. Extra anlagen can be 

 produced at will in an almost mechanical way which is not teleo- 

 logical, for the Stentor may form primordia which it could better 

 do without. Moreover, the number and length of oral formations 

 is clearly not limited by some " critical metabolite " sufficient 

 only for one. Both repeated and multiple regeneration are possible 

 for this cell.* 



3. Abnormal primordia correlated with abnormal striping 



If primordium formation is reUably correlated with loci of 

 contrasting stripe widths, then this should also be manifested in 

 aberrant stentors with unpremeditated misalignments of the 

 patterns of cortical striping, leading to primordia of very abnormal 

 forms. A sampling of such cases is shown in Fig. 47. Perusal of 

 these sketches will show with what persistence all loci of stripe 

 contrast are filled out with primordia, often exceedingly bizarre. 

 Even though the l.s.c. may be very contorted or of extraordinary 



*According to Uhlig (i960) the size of the anlage is also directly corre- 

 lated with the degree of stripe contrast at the primordium site. 



