PLATE 8 



Kg. 5. A secondary membrane formed by the approximation of 

 originally separated cells from the ectoderm of a tadpole of Hyla. 



Pigs. 6, 7. Isolated ectodermie cells from the same preparation from 

 which figure 5 is taken. In 6 there is a long cytoplasmic process ending 

 in a clear amoeboid expansion. 



Pig. 8. Tip of the process shown in figure 4 that extends between the 

 two fibers of cotton ; a, h, c represent successive changes in the hyaline 

 border of the lobe a. 



Figs. 9-11. Stages in the extension and form changes of the tip 

 of the process shown in figure 8. The dotted lines indicate a mark on 

 the micrometer set to gauge the progress of the strand of cells. 



[172] 



