Embryo of Sequoia sempervirens. 17 
After a very careful search I was unable to find the spindle that gives 
rise to the ventral canal-cell nucleus in Sequoia , but enough evidence was 
found to convince me that such a nucleus is cut off from the central nucleus. 
At a stage soon after the neck-cells have been organized, several archegonia 
showed two distinct nuclei in the cytoplasm. As shown in Fig. 22, the 
nuclei are of the same shape and size, and are situated at opposite ends 
of the archegonium. The nucleus at the base of the archegonium becomes 
the egg-nucleus, and there is little doubt that the one nearer the neck-cells 
represents a vestige of the ventral canal-cell. In Pinus and Tsuga a distinct 
cell-plate is formed, which separates the ventral canal-cell from the egg-cell. 
In the majority of the Conifers investigated, however, the ventral canal-cell 
is only represented by a nucleus, no cell-plate being formed. This is evi- 
dently the case in Sequoia , for the ventral canal-cell nucleus functions no 
farther, and very soon becomes disorganized. In one or two archegonia it 
was found more or less flattened against the neck-cells, and in others it was 
more or less fragmented. That this is not the nucleus of the male cell was 
shown quite conclusively by the fact that the neck-cells were in no way 
disturbed. It apparently breaks down soon after it is cut off from the 
central nucleus. By the time the archegonium is ready for fertilization 
the ventral canal-cell nucleus has entirely disappeared. This very short 
period of its existence probably accounts for its having been overlooked 
by Shaw and Arnoldi. 
Soon after the disappearance of the ventral canal-cell nucleus, the egg- 
nucleus moves forward and occupies a position about halfway between the 
centre of the archegonium and the neck-cells. Meanwhile a large vacuole 
is developed in the lower part of the archegonium, as shown in Fig. 23. 
This figure shows a typical mature archegonium ready for fertilization. 
Fertilization. 
It has already been pointed out that the courses taken by the pollen- 
tubes have been well established long before the archegonia have been 
organized. It is therefore obvious that the direction taken by the tubes 
is not at all influenced by the female organ. On the other hand, however, 
it would seem that the pollen-tube had an influence upon the direction 
taken by the developing archegonia, for the growth of these latter structures 
is almost invariably directed towards the nearest tube. Fig. 27 shows how 
the archegonia appear in a cross-section of the prothallium. In this section 
there are four archegonia arranged in a semicircle, and with their neck-cells 
in contact with the wall of the pollen-tube. A longitudinal section would 
show ten to fifteen archegonia in a row, with the neck-cells directed toward 
the tube. The archegonia do not all point toward one tube, but each tube 
— and there are usually three or four present— has a number of archegonia 
directed toward it. Considering the diverse positions occupied by the 
c 
