4/0 MARIE A. HINRICHS. 



DESCRIPTION OF FIGURES. 



PLATE I. FIGS. 1-30. 



Normal Larva. Figs. 1-2. Fig. i, aboral, and Fig. 2, lateral view of normal 

 pluteus, 48 hours after fertilization. 



Differential Inhibition. Figs. 3-24. 



FIG. 3. Eggs exposed 45 minutes in 1/5,000 Eosin. i,5oo-\vatt bulb, at 50 cm. 



FIG. 4. Eggs exposed 15 minutes in 1/5,000 N. red. i,soo-watt bulb, at 

 50 cm. 



FIG. 5. Unstained sperm 10 minutes. i,5OO-watt bulb, at 25 cm. 



FIG. 6. Concentrated sperm i minute. Ultraviolet. 



FIGS. 7-8. Eggs exposed 45 minutes in 1/5,000 N. red. 1,500-watt bulb, at 

 50 cm. 



FIG. 9. Sperm exposed 10 minutes, natural pigment, i.soo-watt bulb, at 

 50 cm. 



FIGS. lo-n. Sperm (dilute) 2\ minutes. Ultraviolet. 



FIG. 12. Sperm (cone.) 2 minutes. Ultraviolet. 



FIG. 13. Sperm exposed 30 minutes, natural pigment. i,soo-\vatt bulb, at 

 50 cm. 



FIG. 14. Sperm exposed 30 minutes in 1/10,000 Eosin. 1,500-watt bulb, at 

 50 cm. 



FIG. 15. Eggs exposed 45 seconds. Ultraviolet. 



FIG. 16. Eggs exposed 45 minutes in 1/5,000 N. red. i.soo-watt bulb, at 

 50 cm. 



FIG. 17. Eggs exposed 15 minutes in 1/5,000 Benzo. i.soo-watt bulb, at 

 50 cm. 



FIGS. 18-19. Sperm exposed 30 minutes in 1/10,000 Eosin. i.soo-watt bulb, 

 at 50 cm. 



FIG. 20. Sperm (cone.) 3 minutes. Ultraviolet. 



FIG. 21. Sperm exposed 2 seconds. Ultraviolet. 



FIG. 22. Sperm exposed 30 minutes in 1/10,000 Eosin. i,5OO-\vatt bulb, at 

 50 cm. 



FIG. 23. Sperm (cone.) 2 minutes. Ultraviolet. 



FIG. 24. Sperm (cone.) 25 minutes. Ultraviolet. 



Differential Acclimation. Figs. 25-30. 



FIG. 25. Sperm (dil.) I minute. Ultraviolet. 



FlG. 26. Sperm (cone.) minute. Ultraviolet. 



FIG. 27. Sperm 10 minutes, natural pigment, i.soo-watt bulb, at 50 cm. 



FIG. 28. Sperm (cone.) i minute. Ultraviolet. 



FIG. 29. Sperm 10 minutes, unstained, i.soo-watt bulb, at 25 cm. 



FIG. 30. Sperm 10 minutes in 1/10,000 Eosin. i.soo-watt bulb, at 25 cm. 



