27 
Embryo of Sequoia semper virens. 
Fig. 14. A longitudinal section of the middle and lower portion of the prothallium, showing the 
accumulation of cytoplasm and free nuclei, and the corresponding decrease in the size of the vacuole. 
The free nuclei have increased enormously in numbers, and are distributed uniformly throughout the 
cytoplasm. June 8, 1902. x 175 - 
Fig. 15. From a longitudinal section of the prothallium immediately after the final division of 
the free nuclei. Each nucleus is surrounded by a system of kinoplasmic radiations in such a way 
that a large number of nuclei are connected together by fibrils. This is the first step in preparation 
for cell-plate formation. June 12, 1902. x 1000. 
Fig. 16. A section of endosperm, showing a stage immediately following that shown in Fig. 1 5. 
The cell-plate has developed from the kinoplasmic fibrils stretching between the nuclei. Between 
some of the nuclei the cell-plate is already fully formed, while in others the granules are seen on the 
fibrils which eventually become the cell-plate. June 12, 1902. x 1000. 
Fig. 17. A longitudinal section of the upper portion of the prothallium, showing the distribution 
of the archegonia. The archegonia are shown in various stages of development. Archegonial 
initials, jacket-cells, and mature archegonia are shown in the same region. The growth of the older 
archegonia is directed toward the periphery of the prothallium. July 8, 1902. x about 150. 
Fig. 18. A longitudinal section, showing a secondary prothallium in an advanced stage of 
development. The primary prothallium has already developed cellular tissue, and the course of the 
secondary appears to wind in and out through this. June 29, 1902. x 150. 
Fig. 19. A cross-section, showing the close relationship between the primary and secondary 
prothallia. The cells of the primary prothallium in contact with the secondary extend outward and 
act as absorbing organs. These cells extend into the protoplasm of the secondary prothallium in 
a dovetail fashion, and their nuclei are very large and have the appearance of being engaged in very 
active metabolism. June 27, 1902. x 100. 
Fig. 20. An archegonial initial in process of division. The spindle shows the large V-shaped 
chromosomes on the way to the poles. The cells resulting from this division are the central cell and 
the primary neck-cell. In order to bring out more clearly the character of the chromosomes, the 
figure was drawn at a somewhat higher magnification than the other figure of the archegonium. 
June 25, 1902. x 850. 
Fig. 21. A young archegonium, showing the large central cell and the small primary neck-cell. 
June 25, 1902. x 750. 
Fig. 22. A later stage of the archegonium, showing two neck-cells. The archegonium contains 
two large nuclei of equal size. The nucleus nearer the neck is the ventral-canal nucleus, and the one 
at the opposite end is the egg-nucleus. June 25, 1902. X 750. 
Fig. 23. A typical mature archegonium ready for fertilization. There are two neck-cells present. 
The ventral-canal nucleus has disappeared, and the egg-nucleus is centrally situated. A large 
vacuole occupies the lower portion of the archegonium. June 29, 1902. x 750. 
Fig. 24. A mature archegonium, showing four distinct neck-cells. June 29, 1902. x 750. 
Fig. 25. A cross-section of a pollen-tube completely surrounded by female prothallial tissue. 
The tube contains the body-cell and the tube- and stalk-nuclei. June 25, 1902. x 150. 
Fig. 26. A cross-section of the upper portion of the female prothallium, showing the position of 
the archegonial initials and jacket-cells when they first become differentiated. June 25, 1902. 
x 100. 
Fig. 27. A cross-section of the upper portion of the female prothallium. The prothallial tissue 
partially surrounds a pollen- tube. Four mature archegonia are shown with their necks in contact 
with the wall of the tube. This position of the mature archegonia in relation to the pollen-tubes 
is very characteristic. June 27, 1902. x 100. 
Fig. 28. A cross-section of the female prothallium, showing sections of their pollen-tubes. As 
shown in this figure, the outline of the prothallium is always modified to the shape and position of 
the pollen-tubes. Two of the tubes show the male cell. June 25, 1902. x 100. 
Fig. 29. A denucleated male cell as it appears after the nucleus has been injected into the egg. 
It retains its spherical form, but the central region once occupied by the nucleus is distinctly vacuo- 
lated. The figure shows quite clearly that only a very small amount of cytoplasm from the male 
cell accompanies the nucleus through the narrow canal between the neck-cells into the egg. June 
25, 1902. x 750. 
Fig. 30. An archegonium immediately after the entrance of the male nucleus. The male nucleus 
is shown pushing in the wall of the female. June 25, 1902. x 750. 
