LIST OF ILLUSTRATIONS 



OPERATING ON A NEWT S EMBRYO 



Frontispiece 



FIG. PAGE 



1. EGG-CELL AND SPERM-CELL 26 



2. ORDINARY CELL-DIVISION 20 



3. cell-division in the formation 



of the germ-cells 29 



4. formation of germ-cells 3i 



5. inheritance of short fingers 33 



6. the effect of yolk on cleavage 36 



7. spemann's tying-up experiment 38 



8. BLASTULA AND GASTRULA OF SEA- 



URCHIN 42 



9. DEVELOPMENT OF THE NEWT ' S EGG 



facing page 48 

 10. vogt's dye experiment on the 



newt's embryo 45 

 ii. maps of the newt and lamprey 



EGGS 46 



12. CULTURE VESSEL FOR EMBRYOS 5I 



13. THE ORIGIN OF THE MESODERM IN 



THE CHICK 52 



14. MAP OF THE CHICK EMBRYO 54 



15. DEVELOPMENT OF THE RABBIT 57 



16. spemann's exchange EXPERIMENT 



IN THE NEWT 65 



