Il 



EXPLANATION OF PLATES 



PLATE 7 



Fig. 1. Extension of ectoderm from a section near the tip of the tail of 

 a Hyla tadpole. The extension of cells, shown more highly magnified in a, 

 proceeds from the middle of the posterior cut surface. 



Fig. 2. Section across the tail of a tadpole of Bana showing a strand 

 of ectoderm extending from the middle of the posterior end, and other 

 strands at the anterior end extending along the surface of the coagu- 

 lated plasma. 



Fig. 3. Lateral extensions of cells from a section of the tail of a 

 tadpole of Bana. The strands in places have widened into sheets of cells. 



Fig. 4. Strands of cells from a tadpole of Bana extending along and 

 between fibers of cotton. 



1 



[170] 



