t 



220 Campbell: The embryo-sac of Pandanus 



Fig. 7. A somewhat older stage; the embryo-sac contains two nuclei, only one 

 of which shows in the section. 



Fig. 8. Embryo-sac with two nuclei ; only one of the sister-cells, x, shows in the 

 section. 



Fig. 9. Embryo-sac with four nuclei ; only one of the micropylar nuclei is seen in 

 the figure- 



Fig, io. Embryo-sac with two micropylar and four chalazal nuclei. 



Plate 17 



Figs. 17-21 refer ic^ Pandamis odoratissifuus L., the others to P. Artocarpus ; 

 all figures drawn with Leitz -^^ oil-immersion, oc. i. Reduced one fourth in repro- 

 duction. 



Fig. II. Embryo-sac having six chalazal nuclei, four oi which are shown in a ; 

 one of the nucellar cells has pushed up into the base of the embyro-sac ; ^, the micro- 

 pylar end of the same sac, showing the two cells, x^ above the sac. 



Fig. 12. a. Micropylar end of an embryo-sac with eight chalazal nuclei ; the re- 

 mains of the two sterile '*megaspores '* are seen above the sac. b. Chalazal end of 

 the same. 



Fig. 13. Transverse section of the chalazal region of an embryo-sac with 8 

 chalazal nuclei. The small cell, j, probably belongs to the nucellus. 



Fig. 14. Upper end of an embryo-sac in which there was an apparent slight dif- 

 ferentiation into a synergid (?), j, and an egg-cell (?), o ; one of the chalazal nuclei is 



seen. 



Fig. 15, Chalazal end of the same sac ; there were probably 12 chalazal nuclei; 

 the small cell, y, probably belongs to the nucellus. 



Fig. 16. Chalazal end of one of the largest sacs that was found — 12 chalazal 

 nuclei were present. 



Fig. 17. Apex of the nucellus of a young ovule of P. odoraiissimus ; the embryo- 

 sac had four nuclei. 



Fig. 18. Micropylar end of the sac shown in Fig. 17 ; one of the two nuclei is 

 shown. 



Fig. 19. Mature (?) embryo-sac showing one of the two micropylar nuclei, and 

 three of the twelve chalazal ones. 



Fig. 20. Transverse section showing six of the twelve chalazal nuclei. 

 Fig. 21. The two micropylar nuclei from the same sac. 



