1907] COKER—DEVKLOPMENT OF SEED IN PONTEDERIACEAE 301 



EXPLANATION OF PLATE XXIII 



gnificat 



one-half in reproduction. 



Figs, 1-12, Heteranihera limosum 

 ovule, showing megaspore mother cell. 



Moth 



Fig. 3. Result of first division of mother cell. X675. 



Fig. 4. The two daughter cells dividing again, X675. 



Fig. 5. Shows four megaspores; the two upper side I 



Fig. 5a. Four megaspores in a row. X675. 



Fig. 6. Four-celled embryo sac. X675, 



Fig. 7. Eight-celled embryo sac. X660. 



Fig, 8. Embryo sac ready for fertilization. X675, 



antipodals 



sperm. X450. 



The 



Fig. II. Longitudinal section of seed coats and superficial endosperm. 



i 



leuron layer; i, inner integument; o^ outer integument; 5, starchy endosperm. 



X780. 



Fig. 12. Cross-section of same. 



h 



Figs. 13-19. Pontederia cordata 



definitive endosperm 



X670. 



Fig. 14. Embryo sac just after said division. X67o, 



tipodals 



sperm 



Fig. 16. Still later stage of same. X670. 



Just before beginning of cell -wall formation 



both 



X150. 



about the same stage as iig, 



X670. 



r 



( 



