PLATE 1 



EXPLANATION OF FIGURES 



1 to 6 Stages in normal division, p., peristome; s., septum; m., membran- 

 elles; g.. and g 2 ., remains of the gullet after dedifferentiation. The gullet is to 

 be considered as made up of the invagination containing the membranelles, sep- 

 tum, etc., in figure 1. g., and g-., are the same as a., and a 2 ., the anlagen of the 

 new gullet. 



7, 8 and 9 Encystment. h., hilum; r., clear body of protoplasm. The upper 

 arrows between figures 9, 8 and 7 refer to the reversal of the morphogentic 

 processes which take place in the protoplasm and not the cyst. 



10 to 15 Stages in the process of regeneration. Figure 10 is partly schema- 

 tized for the sake of clearness, by showing the cut surface as it would appear if 

 it did not close. The arrows show the possible sequence in the processes of 

 dedifferentiation and differentiation. 



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