Role of Preformed Structure in Cell Heredity 169 



two contractile vacuole pores. Each dot represents one cilium and its 

 base or kinetosome; each row of dots represents a row of kinetosomes, 

 i.e, a kinety. In order not to interrupt the account of normal cortical 

 pattern, I am going to describe at once the way the kinetics are grouped 

 into characteristically patterned areas. Much of this description will 

 be readily followed on Figs. \A and IB; but part will at this point 

 have to be taken on faith until I explain more fully (on pages 170 and 

 171 ) some of the details of cortical structure, the cytological technique 

 used in preparing the specimens for study, and just what the dots on 

 the photographs are. 



There are six major groupings of kineties into characteristic fields: 

 one dorsal and five ventral. The whole dorsal surface is a great field 

 of longitudinal and parallel kineties, except where they converge near 

 their ends to the anterior and posterior poles (which do not exactly 

 coincide with the ends of the midlongitudinal axis of the body). The 

 following five main ventral fields are on the sides of the oral meridian: 

 ( 1 ) The anterior right field is composed of kineties that are nearly 

 parallel to the preoral suture. (2) The anterior left field is composed 

 of kineties that are almost perpendicular to the preoral suture. (3) 

 The circumoral field lies in the vestibule and is composed of arched 

 kineties paralleling the edge of the mouth. In ventral views the vesti- 

 bule is seen on edge, making its kineties appear so close together as 

 sometimes to give the impression of a heavy ring around the mouth. 

 (4 1 The posterior right field is composed of kineties that extend 

 parallel to the cytopyge line. (5) The posterior left field includes 

 kineties that meet the cytopyge at an acute angle. Adjacent fields are 

 not sharply set off from one another except where they meet the oral 

 meridian. Thus the two anterior fields grade into the circumoral field 

 and the latter grades into the two posterior fields, especially in the 

 region between the posterior end of the mouth and the anterior end 

 of the cytopyge. Likewise, the distinctive patterns on the right and left 

 of the oral meridian grade into the simple interpolar pattern on the 

 dorsal surface. The five ventral fields and the gullet together will be 

 referred to as the oral segment. 



By far the most complex structure of the ventral surface is its inter- 

 nal extension beyond the mouth into the funnel-shaped gullet or 

 cytopharynx (Fig. 2A ) . Figures 2B and 2C show what appear to be 13 

 kineties, of which a large part of the gullet is composed. (This ap- 

 pearance may be deceptive in the light of the studies of Ehret and 

 Powers (1959), whose descriptions suggest that the number and orien- 

 tation of the gullet kineties may be quite different from the superficial 

 appearances. ) Parallel to the right margin of the mouth, at the June- 



