8 E. J. LUND 



t 



most carefully studied are shown in figures of plates IV and V. 

 They will illustrate the observed phenomena. 



1. Reversal of polarity in hetero?norphic individuals from cut 



pieces 



The individuals described in this section developed from equal 

 anterior, posterior, right or left halves. They are shown in plate 

 4. The following is a transcript of brief notes made at intervals 

 after cutting, giving the history of the pieces. The arrows in the 

 figures indicate the direction of the ciliary currents over the body 

 and in the gullet. 



Experiment 7a. Fifty individuals cut longitudinally. Three of the 

 100 pieces became heteromorphic and are described (plate 4). 



Figures 21a' and 21b are from halves of same individual. His- 

 tory. Six hours after cutting it was irregular. Twelve hours after 

 cutting, triangular, apparently several pieces of nucleus fused; drawn 

 (fig. 21a). Twenty-four hours, heteromorphic, drawn (fig. 21a'). 

 Thirty-six hours, dead. 



Figure 21b. History. Six hours, dedifferentiated. Twelve hours 

 elongated, very abnormal. Twenty-four hours heteromorphic, drawn 

 (fig. 21b). Thirty-six hours, active, protoplasm clear (this was due to 

 starvation). Macronucleus all withdrawn into larger individual; 

 ciliary currents same as at twenty-four hours. The smaller individual 

 was narrower than in figure 21b. Forty-eight hours, thick cyst formed 

 from large individual. Small, spindle-shaped, dedifferentiated, non- 

 nucleated active piece present in watch glass. This was the isolated 

 remains of small individual of the heteromorph at twenty-four hours. 

 Sixty hours; small piece dead. 



Figure 22. History. Six hours, small piece of macronucleus 

 present, dedifferentiated; a trace of an oral groove at each end; beat 

 of cilia indicate heteromorphic condition, drawn (fig. 22). Twelve 

 hours; presence of trace of oral grooves doubtful but ciliary currents 

 and shape as at six hours. Twenty-four hours; irregular, not active. 

 Thirty-six hours, pear shaped, active. Forty-eight hours, cyst, dead. 

 The sister piece regenerated after thirty-six hours to a perfectly normal 

 individual which lived eighty-four hours. 



Experiment 5. Fifty individuals cut longitudinally. Two of the 

 100 pieces became heteromorphic. These two pieces were halves of the 

 same individual. 



Figure 23a. Twenty-four hours after cutting it was heteromorphic. 

 One large gullet and mouth nearly normal. The other end had a small 

 oral groove with no membranelles, ciliary currents opposite, drawn. 

 Forty-eight hours, normal, all ciliary currents in same direction. The 



