Castle. — Ciona intestiualis. 



PLATE XII. 



Magnification of all Figures, 5(30 diameters. 



Figs. 84-87. Four cross sections from a series tlirough a gastrula with wide-open 

 blastopore. 



Fig. 84. Section posterior to the blastopore. 



Fig. 85. Section througii the posterior portion of tlie blastopore. 



Fig. 86. Section through the anterior i)oriion of tlie blastopore. 



Fig. 87. Section anterior to tiie blastopore. 



Figs. 88-92. Five cross-sections tliroiigh an embryo with greatly contracted blasto- 

 pore ; Figs. 88 and 89 posterior to blastopore ; Figs, yi and 92 an- 

 terior to blastopore. 

 iVo^e. — The large unstippled cell in the left half of Fig. 88 sliould have been 

 stippled. 



Figs. 93-97. Five cross sections through a sliglitly older embryo. Compare vertical 

 lines 93-97 in Fig. 98. Fig. 93, section posterior to blastopore; 

 Figs. 95-97, sections anterior to blastopore. 

 Note. -The large unstippled cell in the left half of Fig. 93 should have been 

 stippled, likewise two large cells situated laterally in Fig. 95, one in either half 

 or the figure. 

 Fig. 98. Sagittal section through an embryo with nearly closed blastopore. 



