first poior body 



seco nd polorbody 



spireme 



first cleavaqe 



anaphase 



biastula 



pronuclei 



chromosome 



early prophase 



late prophase metaphase 



Telophase restinq cells 



morula 



Ectoderm 

 endoderm 



early qastrula 



s ^ ' k'^v^''^ ' ^'']^'' ' ^' ' ''M:» *,J^^^G canal 



late qastrula 



mesoderm 



coelome notochord 



primitive qut 



Fig. 23-2. Fertilization and early embryology of Amphioxus is shown in this series of figures. 



