— Plate 19. — 



Figs. 1-23. — Aldrovanda vesiculosa. 

 Figs, i, 2 and 3. — Stages of germination. 

 Fig. 4. — Apex of root cap showing its obsolescence. 



Pjc 5. — a series of juvenile leaves such as at first formed on the plu- 

 mule; the perfect, mature form on the right. 

 Fjg. 6. — The development of the leaf showing the early occurrence of 

 twisting which brings the trap into its definitive posture. E, F and H, 

 dorsal views; G, ventral view. 

 jTjg 7 _ Immature trap, as in riG. 5, showing the curvatures which, be- 

 coming fixed, determine the behavior of the trap during narrowing. 

 Fig. 8. — Interior (upper) face of a trap lobe. Distribution of cruciform 

 and digestive glands shown, as also the sensitive hairs and reflexed 

 lobe margin, with its teeth. 

 Fig. 9. — Transverse section through a footstalk (petiole), showing vast 



intercellular spaces. 

 Fig. 10. — Section through the midrib of a trap. 

 Fig. II. — Transverse section through the wall of a trap in the region 



marked 2, fig. 23. 

 Fig. 12. — Three sections through the reflexed margin of the trap. Note 



the irregularity of structure. 

 Fig. 13. — The reflexed margin of trap with tooth. 

 Pjq j4 — Digestive gland viewed from above and laterally; a and b are 



are normal to each other. 

 Fig. 15. — A cruciform gland. 



Pjg. 16. — A mucilage gland from the outer surface of the trap and else- 

 where. 

 Pic 17. — Surface view of the reflexed lobe margin, showing the cells of 

 one surface intruding between those of the other. The arrowpoints 

 indicate inward or outward intrusion. 

 Fig. 18. — Crossing of marginal spines to close the trap against the escape 

 of prey. The posture of the teeth in this figure is exaggerated in rela- 

 tion to the borders, but represents what does occur during early 

 approach of the edges. 

 Fig. 19. — Transverse section of the wall of the trap in the region be- 

 tween 3 and 4, fig. 23 of this plate. The component cells are cut 

 longitudinally. 

 Fig. 20. — A trigger hair (above and to the right of the numeral). 

 Fig. 21.- Diagrams showing (a) open, (b) closed, (c) early narrowing 

 and {d) completely narrowed stages of action. After Ashida, checked 

 by my own observations. 

 Fig. 22. — Diagram to show zone of major movement during closing and 



narrowing. ^ , • 1 j 



Pjc. 23. — Diagram of transverse section of a trap to show the thick and 

 thin regions, the distribution of digestive and cruciform glands, and 

 of the trigger hairs. 



