THE ORGANEER 



199 



PRESUMPTIVE MEDULLARY PLATE 



DORSAL LIP 

 BLASTOPORE 



ANURA STAGE I I 



SHOWING REGIONS TO BE EXCISED OR TRANSPLANTED 



ORGANIZING IMPLANT 



VENTRAL LIP 



HOLTFRETERS' SOLUTION 

 BLASTOCOELE 



ORGANIZING IMPLANT 

 VENTRAL LIP 



•GASTRULAR SLIT 



DORSAL UP 



STAGE 10 



DORSAL UP 



HOLTFRETERS' SOLUTION 

 BLASTOCOELE 



NOTOCHORD 



lEDULLARY PLATE 

 STAGE 12 



