7 
Embryo of Sequoia sempervirens. 
nucleus. During the further development of the pollen-tube, the three 
nuclei remain in close proximity to each other. During these changes the 
size of the tube-nucleus remained the same, while that of the stalk-nucleus 
increased slightly. The body-nucleus, however, increased to at least 
three or four times the size of the stalk-nucleus, as shown in Fig. 5. 
During its development the body-nucleus surrounds itself with a dense 
zone of granular cytoplasm. This zone increases until it is about half the 
diameter of the nucleus in thickness, when it becomes shut off from the 
rest of the cytoplasm in the tube by a distinct membrane. The tube now 
contains one large cell and two free nuclei (Fig. 6). 
Previous to the formation of the body-cell, the free nuclei lie close 
together suspended in the same strand of cytoplasm, which contains an 
abundance of starch. The most of the starch was present in the vicinity 
of the body-nucleus, and it later becomes confined within the cytoplasm 
of the body-cell. The stalk-nucleus remains close to the body-cell (Fig. 5), 
even up to the time the male cells are formed. 
The changes resulting in the organization of the body-cell showed 
considerable variation as to the time of their occurrence. In some cases 
the mature body-cell was found in material collected early in May, while 
others were found as late as the middle of June. This irregularity as to 
the time of the changes was also noticeable in all later changes in the 
development of the male prothallium, even in the matter of fertilization. 
Soon after the body-cell has been fully organized, its nucleus enlarges 
and prepares for division. By extreme good fortune the spindle of this 
division was found. As this is the division which results in the formation 
of the two male cells, it demands a careful examination. It was during 
the division of the body-cells in Cycas , Zamia , and Ginkgo (Hirase, 1898 ; 
Ikeno, 1896-8; Webber, 1897-1901) that the centrosome-like bodies 
known as blepharoplasts were discovered. It was thought probable that 
a vestige of such an organ might be found in Sequoia , , but an examination 
of the cytoplasm surrounding the spindle failed to reveal a trace of any 
body that might be interpreted as a blepharoplast. It must be remembered, 
however, that the blepharoplasts are only concerned with the development 
of the cilia, and as these latter structures have never been found in con- 
nexion with the male cells in Conifers, it is not surprising that the organs 
responsible for their formation should also be missing. Fig. 7 shows the 
spindle dividing the body-nucleus with the daughter-nuclei at the poles. 
The formation of the cell-plate that separates the nuclei and divides the 
body-cell into two was not actually observed. But an examination of 
Fig. 7 where the connective fibrils curve out laterally, and of Fig. 8 where 
the two daughter-cells are lying side by side, makes it obvious that the 
cell-plate is developed in the usual way. After the wall separating the 
male cells has been formed, the latter remain close together for some 
