22 
Lazuson . — The Gametophytes , Fertilization and 
EXPLANATION OF FIGURES IN PLATES I— IV. 
Illustrating Dr. Lawson’s Paper on Cephalotaxus, 
All figures were drawn with the aid of the camera Lucid a. The following oculars and objectives 
were used. 
Figs, i, 2, 6, 7, 8, 12, 19, 21, Zeiss oc. 1, obj. oil imm. T V 
Figs. 3, 44, Zeiss oc. 2, obj. 3. 
Figs. 4 > 5> 9> 10 > Zeiss °c. 3? obj. 3. 
Figs. 11, 13, 14, 15, 16, 24, Zeiss oc. 1, obj. 3. 
Figs, 17, 18, 20, 22, 26, 27, 28, 29, 30, 31, 32, 34, 36, 37, 38, 39, 40, 41, 42, 43, Zeiss oc. 6, 
obj. 3. 
Fig. 25. Zeiss oc. 4, obj. 3. 
Fig. 23. Zeiss oc. 4, obj. 7. 
Fig. 33. Zeiss oc. 2, obj. oil imm. X V 
Fig. 35. Zeiss oc. 6, obj oil imm. -fa. 
Fig. 1. A cross-section of a microspore some time before pollination, showing the single large 
nucleus and the presence of starch granules. March 7, 1904. 
Fig. 2. A cross-section of a microspore just before pollination showing the tube and the 
generative nucleus. 
Fig. 3. A longitudinal section of the ovule at the time of pollination showing the mega- 
sporangium, integument, and micropyle. April 19, 1904. 
Fig. 4. A longitudinal section through the upper part of the nucellus showing a young pollen- 
tube containing the body-cell B., and the stalk and tube-nuclei t. May 11, 1904. 
Fig. 5. The same ten days later showing a pollen-tube that has completely penetrated the 
nucellar tissue with the body-cell, and the stalk and tube-nuclei in the distended tip of the tube. 
May 21, 1904. 
Fig. 6. A tip of a pollen tube more highly magnified showing the character of the cytoplasm in 
the tube and in the body-cell, and nucleus of the latter preparing for division. May 21, 1904. 
Fig. 7. The two sperm-nuclei resulting from the division of the body-cell nucleus. They occupy 
the greater part of the cavity of the body-cell, the old membrane of which still envelops them. The 
stalk and tube-nuclei are also present. May 23, 1904. 
Fig. 8. Two sperm-nuclei showing the characteristic way in which they fold over each other^ 
May 26, 1904. 
Fig. 9. A longitudinal section of a very young prothallium. The single embryo-sac consists of 
a thin parietal layer of cytoplasm and a large central vacuole. 
Fig. 10. The same as above at a later stage. 
Fig. 11. A later stage in the development of the prothallium showing the primary prothallial 
cells growing in and closing the vacuole. 
Fig. 12. A highly magnified section of a part of the parietal layer of cytoplasm taken from the 
stage represented in Fig. 9. 
Fig. 13. A longitudinal section through the upper region of a young prothallium showing a young 
archegonium with one neck-cell. April 27, 1904. 
Fig. 14. A longitudinal section as above with two neck-cells in the archegonium and a single 
layer of jacket-cells already organized. 
Fig. 15. A cross-section through the’ neck region of the archegonia. Two of the four show 
three cells in the neck, the remainder only two. May 21, 1904. 
Fig. 16. A cross-section through the middle region of the archegonia showing their characteristic 
perfectly circular form in section and each enveloped in a single layer of jacket-cells. May 21, 1904. 
Fig. 17. A longitudinal section of an archegonium with the central nucleus preparing for 
division. May 23, 1904. 
Fig. 18. A longitudinal section of an archegonium with the central nucleus in the early stage 
of division. Spindle formation has begun. May 26, 1904. 
