Organs and Fertilization in Picea excelsa . 371 
EXPLANATION OF FIGURES IN PLATES XVI 
and XVII. 
Illustrating Dr. Miyake’s paper on Picea excelsa . 
All figures were drawn with the aid of a camera lucida, using Zeiss’s and Bausch 
and Lomb’s microscopes. The abbreviations used are : g.c., generative cell ; 
s.c., stalk-cell ; t.n., tube-nucleus ; s.p}, first sperm-nucleus ; sp. 2 , second sperm- 
nucleus ; v.c.c., ventral canal-cell ; e.n ., egg-nucleus. 
PLATE XVI. 
Figs. 1-6. Pollen-grains in different stages of development, a few days before 
pollination. Fig. i. The central cell is still undivided. Figs. 2-5. Various 
stages in the division of the central cell. Fig. 6. A stage after the division of the 
central cell, p ., disintegrating prothallial cells ; c.c., central cell, x 250. 
Fig. 7. A pollen-grain about to germinate, x 250. 
Fig. 8. The same, later stage, x 250. 
Fig. 9. A pollen-grain soon after germination ; the tube-nucleus is just moving 
down the pollen-tube, x 2 50. 
Fig. 10. A later stage ; the generative cell is considerably enlarged, and the 
tube-nucleus is found near the tip of the pollen-tube, x 250. 
Fig. 11. Upper portion of a germinating pollen-grain, a little before the passage 
of the stalk- and generative cells into the pollen-tube. Starch-grains are found 
in the stalk-cell, x 250. 
Fig. 12. A later stage; showing the passage of the stalk- and generative cells 
into the pollen-tube, x 250. 
Figs. 13, 14. Later stages than in the above ; the stalk-cell has already passed 
over the generative cell, and is found at the lower side of the latter, x 250. 
Fig. 15. Division of the generative cell, x 250. 
Fig. 16. The sperm-nuclei just after their formation; the spindle with a cell- 
plate is seen between them, x 250. 
Fig. 17. Similar stage, but little later; two nuclei are much more separated. 
The remnants of the spindle are seen near the upper nucleus, x 250. 
Fig. 18. The two sperm-nuclei are approaching each other ; remains of the 
spindle are still seen, x 250. 
Figs. 19-21. The sperm-nuclei after all traces of the spindle have disappeared, 
lying in the upper part of their cytoplasm, x 2 50. 
Fig. 22. The full-grown sperm-nuclei near the tip of the pollen-tube ; the tube 
is almost approaching the archegonium. x 250. 
Fig. 23. An archegonial initial, x no. 
Fig. 24. The same, later stage ; the nucleus is preparing to divide, being in the 
spireme stage, x no. 
Fig. 25. Nucleus of the archegonial initial is just dividing, x no. 
Fig. 26. After the division ; the larger central cell and the smaller mother-cell 
of the neck are formed, x no. 
Figs. 27-31. Later stages in the development of the archegonium. Fig. 31 
