PLATE 3 



EXPLANATION OF FIGURES 



19 Longitudinal sagittal section of a fully differentiated individual, -p. , 

 peristome; m., membranelles; g., gullet; /., food vacuole; mn., rnacronucleus; 

 v., ventral; d., dorsal. 



20 Horizontal longitudinal section of a spontaneously dedifferentiated nor- 

 mal individual. Dedifferentiation more complet than at the stage shown in 

 figure 2. a., anlage of the gullet; mn., macronulceus. Micronuclei not shown. 



26 



