260 W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 



Fig. 10, 12. Transverse sections of loculi of somewhat more developed anthers 

 of Z. minor. Magn. 200 diam. 



Fig. 11, A collection of young pollen-cells of ^. marina, Magn. 400 diam. 



Fig. 13. A few somewhat further developed pollen-cells of the same species, 

 isolated in concentrated solution of carbonate of ammonia. Magn. 

 400 diam. 



Fig. 14. Longitudinal section of the lower part of an anther-loculus of Z. minor. 

 Magn. 300 diam. 



Fig. 15, Piece of a mature pollen-cell of Z. marina. The ascending current of 

 protoplasm is shown darker, the descending lighter. Magn. 400 diam. 



Fig, 15 b. Pieces of mature pollen-cells exhibiting protrusions of all kinds (see 

 page 245). Magn. 200 diam. 



Fig. 16. Very young ovaries of Z. marina, seen from above; a, rudiment of 

 the ovule. Magn. 300 diam. 



Fig. 17, 18. Subsequent stages of development of the ovary, in longitudinal 

 sections. Magn. 100 diam. 



Fig. 19. Ovules and the surrounding parts of the walls of the ovary, in longi- 

 tudinal section. Magn. 320 diam. The pendent ovule is here re- 

 presented reversed and upright, as in all the succeeding figures. 



Fig. 20, 21. Longitudinal sections of the nuclei of more developed ovules. 

 Magn. 300 diam. 



Fig. 22. Longitudinal section of an ovule ready for impregnation. The for- 

 mation of the cells compressed into the chalazal end of the embryo- 

 sac has not taken place here. Magn. 320 diam. 



Fig. 23. Longitudinal section of an ovule of the same species ripe for impreg- 

 nation. Magn. 180 diam. 



Fig. 24. Micropyle and upper end of the embryo-sac of an ovule in longitudinal 

 section, at the moment when the pollen-tube has penetrated to the 

 membrane of the sac. Magn. 300 diam. 



Fig. 25. A similar preparation, a little later, with the impregnated germinal 

 vesicle divided into an upper, large suspensor cell, and a lower, small 

 embryonal cell. Mag. 300 diam. 



Fig. 26. A similar preparation with the embryonal globule, composed of 16 cells, 

 represented in longitudinal section. During the observation the 

 suspensor and the embryonal globule slipped from the micropyle end 

 of the embryo-sac as far as *, without perceptible external cause. 

 Magn. 300 diam. 



Fig. 27. Lateral view of a further developed embryonal globule with the 

 suspensor. Magn, 400 diam. 



Fig. 28. A similar embryonal globule, in longitudinal section, at right angles 

 to the projection of the preceding figure. Magn. 400 diam. ♦ 



Fig. 29. Front view of an embryo with suspensor of Z. minor, shortly before 

 the origin of the leaf-bearing axis. Magn. 60 diam. 



Fig. 30. Lateral view, 60 diam. ; fig. 31. front view, of farther developed em- 

 bryos of the same species. Magn. 40 diam. 



Fig. 32. Lateral view of the embryo of a half-ripe seed of the same species. 

 The outline of the secondary axis is indicated by delicate lines, show- 

 ing through the lateral wing of the primary axis. Magn. 40 diam. 



