184 Edwin G. Conklin. 



Quarter Embryos; 16 Cells to Young Tadpole Stage. Fixed an'd Stained Preparations. 



Fig. 59. Left anterior and right posterior (diagonal) quarter embryos of the i6-cell stage, ventral 

 view. 



F"ig. 60. Left posterior quarter embryo of the 44-cell stage, posterior view. 



Fig. 61. Right anterior quarter embryo of the 76-cell stage, dorsal view, showing the neural plate 

 and chorda cells of the right side. 



Fig. 62. Right posterior quarter embryo of about the 180-cell stage, dorsal view {cj. Figs. 7, 8); 

 spurted in the 4-cell stage, fixed 2* hours later, showing 6 muscle and 2 caudal endoderm cells. 



Fig. 63. Left anterior quarter embryo, dorsal view; spurted in the 4-cell stage, fixed 5 hours later. 

 An invagination of the ectoderm cells has the appearance of a gastrula, but is probably the invagination 

 of the neural plate. 



Fig. 64. Left anterior and right posterior (diagonal) quarter embryos, dorsal view; spurted in the 

 4-cell stage, fixed 5 hours later. Muscle cells are found only in the posterior quarter. 



