PLATE 3 



EXPLANATION OF FIGURES 



18 U. setigera. Dorsal view of about the same stage as shown in figure 17. 

 From a stained preparation. 



19 U. setigera. Dorsal view of a mid-division stage. From a stained prepa- 

 ration. 



20 U. setigera. Ventral view of a mid-division stage. From a stained 

 preparation. 



21 U. setigera. Ventral view of the daughter cells just ready to separate. 

 From a stained preparation. 



22 U. setigera. An individual which was cut in such a way that the micro- 

 nucleus was destroyed. The specimen was stained thirty-six hours after cutting. 



23 U. setigera. An individual which was cut in a median transverse plane at 

 an early division stage. The micronucleus was evidently destroyed. Regenera- 

 tion was complete. Experiment no. 3. 



24 U. setigera. Another individual cut as in the case of experiment no. 3. 

 Experiment no. 65. 



25 U. setigera. A monster resulting from a cell injured in an early division 

 stage. Experiment no. 114. 



26 U. setigera. An abnormal cell which developed as the result of a cut 

 which almost separated the two pieces. They rotated on each other and fused as 

 shown. 



27 U. setigera. A cell which had the posterior cirri cut and which did not 

 regenerate them until division. This sketch was made twelve hours after the cirri 

 were cut. 



28 U. setigera. A monster which developed from one of the amicronucleate 

 cells of experiment no. 131. 



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