324 CALIFORNIA ACADEMY OF SCIENCES. [PROC. 3D Ser. 



EXPLANATION OF PLATE XLVL 



All figures except i and 4 were studied with Leitz lenses and drawn 

 with a Zeiss camera. All figures slightly reduced. 

 Figs. 4, 5, 7, 15 and 23 refer to Sparganium Greenii Morong, the 

 others to S. simplex Huds. 



Fig. I. Two female flowers of 5". simplex enlarged about eight times; the 

 one at the right with the perianth removed. 

 A single scale of the perianth more enlarged. 

 Longitudinal section of the ovary showing the single ovule; ma, 



embryo-sac. Oc. i, obj. 3. 

 Pistil of .S". Greenii; X about 8. 

 Section of the ovary of^. Greenii. Oc. i, obj. 3. 

 Sections of ripe pollen-spores of S. sitnplex, showing the large vege- 

 tative, and smaller generative, nucleus; pr, prothallial cell. Oc. 

 I, im. xV- 



Fig. 7. Sections of younger pollen-spores of S. Greenii; the nucleus is still 

 undivided, and no prothallial cell is visible. The clear space on 

 the surface probably marks the place of exit of the pollen-tube. 



Fig. 8. Upper part of the embryo-sac of 5. simplex just after the entrance 

 of the pollen-tube; o, the egg-cell; sy, one of the synergidae; pt, 

 pollen-tube. Oc. i, im. ^^. 



Fig. 9. Another section of the same embryo-sac; the small dark body 

 within the synergid is probably one of the generative nuclei from 

 the pollen-tube. 



Fig. ID. The antipodal end of the same embryo-sac, showing the single large 

 endosperm-nucleus and two of the antipodal cells. 



Fig. II. The egg-apparatus and endosperm-nucleus from a mature embryo- 

 sac. Oc. I, im. j',j. 



Fig. 12. (a) Two antipodal cells from a mature embryo-sac; [b) outline show- 

 ing the position of the three small antipodals. Oc. i, im. y'.j. " 



Fig. 13. Section of the egg-apparatus showing the entrance of the pollen- 

 tube, pt. A small body (the generative nucleus ? ) is visible 

 within the egg; both synergidae are still intact. Oc. i, im. y'j. 



Fig. 14. Another section of the same; the pollen-tube has apparently dis- 

 charged a small granular mass into the embryo-sac. 



Fig. 15. Section of the nucellus and mature embryo-sac oi S. Greenii. Oc. 

 I, obj. 7. A large cell (an extra antipodal ? ), lies above the three 

 antipodal cells. 



Fig. r6. The antipodal region of fig. 16 more highly magnified. 



Figs. 17 and 18. Two sections of the egg-apparatus of .S". Greenii. Oc. i, 

 im. xV- 



Fig. 19. Embryo-sac of 6". Greenii, showing egg, o, and two antipodals, ant. 

 Oc. I, obj. 7. 



Fig. 20. Unusually large sac of the same species; the section shows the two 

 synergidae and the still separate polar nuclei. Oc. i, obj. 7. 



Fig. 21. Two of the antipodal cells from the same sac more highly 

 magnified. 



Fig. 22. Section of egg-apparatus of .S". Greenii. Oc. i, im. xV- 



Fig. 23. Endosperm-nucleus from a similar sac. 



