644 
Miyake and Yasui.—On the Gametophytes and 
The Embryo Formation. 
Fertilization takes place about the end of June. The actual fusion of 
the sexual nuclei was not observed. But various stages of the embryo 
formation were followed. The process does not differ from the usual 
Abietineae type. The result of the division of the fusion nucleus is shown 
in PL XLVIII, Fig. 25. The two daughter nuclei soon divide, and the four 
free nuclei of the proembryo now move down towards the base of the 
archegonium (Fig. 26). Upon reaching the base of the egg, the four 
nuclei arrange themselves in a plane, as shown in Fig. 27. They then 
undergo further division, and the walls are formed between the eight 
daughter nuclei. Thus a tier of four completely walled cells is cut off 
below, and the upper four nuclei being separated from one another by 
walls are exposed above to the rest of the egg cytoplasm (Fig. 28). 
The eight nuclei divide once more, and eventually there are formed 
four tiers of cells of four cells each, the upper tier being incompletely 
walled, since the nuclei are separated from one another by walls, but freely 
exposed above to the unsegmented part of the egg (Figs. 29, 30). The 
lowest tier forms the embryo proper, the tier above is elongated to form 
the suspensor, and the uppermost of the completely walled tiers constitutes 
the rosette (Fig. 31). The young embryo in Fig. 31 is apparently in eight¬ 
cell stage. 
Summary. 
The mature pollen-grain has wings and contains the large tube cell, 
smaller generative and stalk cells, besides the disintegrated remains of two 
prothallial cells. The stages of division in the formation of these cells 
were observed. The number of chromosomes was found to be twelve. 
Pollination takes place in Northern Italy about the middle or the end 
of April, and it seems to be somewhat later in Southern Germany. The 
further development of the male gametophyte after pollination has not 
been investigated. 
The formation of the megaspores seems to occur about the time of 
pollination, the megaspore mother-cell being usually solitary in each ovule. 
The lowest of a row of megaspores develops into the female gametophyte. 
The large central vacuole of the young female prothallium seems to 
be formed already at one-cell stage. The enlargement of the functional 
megaspore goes hand in hand with the free nuclear division. 
The young female gametophyte is surrounded by several layers of 
well-developed tapetal cells, which later show signs of disintegration. 
The megaspore membrane is well developed in the mature prothallium 
and has about the same structure and thickness as that of other Abie¬ 
tineae. It is quite thick in the basal region and thins out gradually 
towards the micropylar region of the prothallium. 
