LIST OF ILLUSTRATIONS. 



FIG. PAGE 



1. Pineal eye of lizard (ffatteria) (after Spencer) ... 34 



2. Pineal eye of lizard, in section (after Spencer) . . 34 



3. Head of horned toad (Phrynosomd) (after nature, by 



W. S. Atkinson) 35 



4. Conjugation of Infusoria (after Leuckart) ... 92 



5. Karyokinesis of cell (after Driiner) . . . . . 155 



6. Reduction of chromatin in egg-cleavage (after Boveri) . 160 



7. Development of Pandorina (after Pringsheim) . . 165 



8. Colony of Rudorina with antherozooids (after Goebel) . 167 



9. Diagram of development of spermatozoa (after Boveri) . 172 



10. Fertilization of egg (after Boveri) 174 



n. Reduction of chromosomes in developing egg (after 



Brauer) ' . . . 180 



12. Maturation of egg of Cyclops (after Rlickert) . . . 182 



13. Larva of Echinus (after Boveri) 187 



14. Hybrid larva of Echinus and Spharechinus (after Boveri) 189 



15. The arctic birch (after nature, by Anne L. Brown) . . 209 



16. Skeleton of greenling (Hexagrammos) (after nature, by 



W. S. Atkinson) 224 



17. Skeleton of scarlet rock-fish (Sebastodes) (after nature, by 



W. S. Atkinson) 224 



18. Skeleton of angel fish (Angelichthys) (after nature, by 



W. S. Atkinson) 225 



19. Sacculina after leaving the egg (after Lang) . . . 279 



20. Sacculina attaching itself (after Lang) .... 280 



21. Sacculina, an early stage (after Lang) .... 280 



22. Sacculina after absorption of limbs (after Lang) . . 280 



23. Adult Sacculina attached to crab (after Lang) . . . 281 



2 xvii 



