SNGLt CELLS 



V}mV CLLLS 



TWO LAVmS 



JWLL LAVERS 

 COE-LOn 



SLonmwioN 



OnOAN SV5Tm5 



NOTOCUOUD 

 GILL SLHS 



sac 



Fiq 25-10. The Biogenetic law can be demonstrated by comparing the embryological stages in the 

 development of a complex animal, such as a vertebrate, and adult representatives of certain of the 

 phyla. Each higher form reenacts the long history of the race in its ov/n embryology. 



