Miyake, The development of the gametophytes etc. 
5 
slowly downward following the tube-nucleus which was previously 
found in the tuhe (figs. 28, 30, 31). 
The stalk-nucleus now advances slightly ahead of the body- 
cell and comes very close to the tube-nucleus. The stalk-nucleus 
which was at first smaller than the tube-nucleus, soon approaches 
the latter in size, and as the both nuclei are of the same structure, 
it is almost impossible to distinguish one froin the other in the 
later history of the pollen-tube (figs. 31—34). As the body-cell 
moves down the pollen-tube, following the stalk- and tube-nuclei, 
it becomes more or less elongated and increases much in size; it 
has no definite cell-wall and often assumes a more or less irregulär 
outline (figs. 31, 32). 
The downward growth of the pollen-tube is at first relatively 
slow and at the later stage of the development it is much ac- 
celerated. Fig. 31 shows the stage when the pollen-tube is about 
half way advanced the nucellar tissue in the middle of June, and 
in fig. 32 we have the tube which has almost completed the 
Penetration of the nucellus in the end of June. 
About the end of June, the pollen-tube reaches the female 
prothallium and soon penetrates into the depression just above the 
archegonial complex (figs. 70, 111). The body-cell, which is now 
very much enlarged and almost spherical in shape, lies at the en- 
larged tip of the pollen-tube. The tube- and stalk-nuclei are found 
just below the body-cell, being imbedded in the granulär cytoplasm 
with numerous starch-granules (figs. 33, 34, 106 a, 106 b). 
The body-cell has a large nucleus surrounded by the dense, 
finely granulär cytoplasm. The nucleus has a prominent nucleolus 
and a well marked reticulum (figs. 34, 106 a, 106 b). As the cell 
prepares for the final division, it becomes more or less elliptical 
in outline. The figures showing the stages of the division were 
not found. The division takes place usually during the first few 
days of July. Figs. 35 and 107 show the sperm-cells which are 
completely organized. The two sperm-cells are of the same shape 
and of equal size. Fach sperm-cell has a large nucleus and the 
latter is surrounded by a dense mass of cytoplasm containing 
abundant starch-granules. In the mature sperm-cell, as shown in 
fig. 35, the starch-granules are often arranged in a dense sheath 
immediately surrounding the nucleus and a clear area is seen in 
the periphery of the cell. A similar arrangement of the starch in 
the sperm-cell has been observed by Coker (1903, p. 11 and 
fig. 31) in Taxodium. When the sperm-cells are fully formed, 
fertilization takes place almost immediately. 
The development and structure of the male gametophyte of 
Cunningliamia above described agree on the whole with those of 
Taxodium (Coker, 1903), Oryptomeria (Lawson, 1904b) and the 
Cupressineae (Land, 1902; Lawson, 1907; Noren, 1907). 
Formation of the Megaspore. 
The pistillate cones appear as inconspicnous buds at or near 
the apex of shoots of the same year, in autumn. The ovules, as 
