416 Lawson .— The Garnet op hyies and 
the second mitosis takes place, which follows closely upon the first. The 
resulting four free nuclei now pass to the base of the archegonium before 
the third series of divisions occur (Fig. 52). During their passage to the 
base all four nuclei enlarge. The next stage observed was that represented 
in Fig. 53, where another division has taken place just before the base of 
the archegonium has been reached. The next division results in the 
formation of cell-walls between the nuclei. As in the Pinus and other 
Abietineae, there are three tiers of cells and one tier of free nuclei constituting 
the pro-embryo. The middle tier of cells develops into suspensors and 
the end tier is carried forward in the ordinary way. Before the elongation 
of the suspensors, however, the cells of the end tier divide repeatedly, forming 
three or four rows which taper to a point. Fig. 54 represents an older 
stage where the suspensors are very much elongated and pushing forward 
a large group of embryo cells at the end. Arnoldi (’ 01 ) describes an 
additional stage where buds and smaller secondary suspensors are given off 
from these cells. This I was unable to find. But this was probably 
because I did not collect material later than July 7, and the stage of 
development at that date is represented in Fig. 54. I hope in another 
season to confirm this interesting later development of the embryo described 
by Arnoldi. 
On the whole the embryo of Sciadopitys is rather unique; it does not 
bear a close resemblance to either the Abietineae, Cupressineae, or Taxaceae. 
Summary. 
At pollination the microspores have already germinated. Each one 
has a very thick exine and a thin inner wall which surround two cells, 
the generative cell and the tube cell. 
At this time the integument of the ovule projects very slightly above 
the level of the nucellus in such a manner as to form a wide but shallow 
micropyle. 
The upper part of the nucellus becomes differentiated into a loose 
tissue of large thin-walled cells for receiving the pollen. This structure has 
been called the pollen-cushion. 
As soon as the pollen-grains have been received they send out tubes 
which penetrate the soft tissue of the cushion. 
The generative cell now divides, giving rise to a large spherical body¬ 
cell and free stalk-nucleus. 
At the end of the first season’s growth, which closes about the middle 
of July, the male gametophyte contains three nuclear structures, viz. the 
tube-nucleus, the stalk-nucleus, and the body-cell. No further nuclear 
changes take place until the following spring. 
In June of the next year the body-cell descends towards the tip of the 
pollen-tube, which, meantime, has entered an archegonial chamber. 
