4 Miyake; The development of the gametophytes etc. 
the poles, they appear as two thick and bent double rods (figs. 10, 
11). Fig. 12 sbows tbe chromosomes as tbey accumulate in both 
poles of the spindle; the daughter-nuclei are then organized as 
shown in fig. 13. 
The daughter-nuclei, between which no wall is formed, soon 
become ready for the next division. The two spindles of the second 
division, are either parallel or perpendicular to each other. Yarious 
stages of the division are shown in figs. 14—18. After the four 
grand-daughter-nuclei are completely formed, walls appear between 
them and thns four pollen-cells or microspores are organized. Ultima- 
tely a fresh wall is formed aronnd each cell, and the microspores then 
separate from each other by the dissolution of the original walls 
(fig. 19). After the microspores are separated from each other, 
they undergo a rapid growth and the walls become considerably 
thickened (fig. 20). The fully-formed microspore is a more orless 
spherical cell with a prominent nncleus; the nucleus usually contains 
a nucleolus. The w T all of the microspore seems to consist of a thin 
exine and a thick intine (figs. 20, 21). 
Development of the Male Gametophyte. 
Pollination begins, as a rule, in the first few days of April, 
though the date differs somewhat by season as well as by locality. 
In Kyoto one tree has begun to shed the pollen on April 4 in 1906. 
In Tokyo pollination began in two different trees on April-1 in 
1908. It usually lasts abont ten days or two weeks. The pollen- 
grain, at the time of pollination, contains two nuclei unequal in 
size. The larger one represents the vegetative or tube-nucleus, 
and the smaller one corresponds to the generative nucleus. The 
two nuclei are separated from each other by a delicate plasmic 
membrane (fig. 26). The division in the formation of these two 
nuclei or cells seems to take place a few days before pollination. 
Yarious stages of the division are shown in figs. 22—25. The 
absence of the sterile prothallial cells seems to be the rule among 
the Taxodieae and the Cwpressineae. The same thing is also found 
in the Taxeae 1 ). In other groups of the Coniferae , one or two 
prothallial cells are usually formed. 
A few days after pollination, the pollen found at the apex 
of the nucellus begins to send out tube. The pollen-tube, pene- 
trating the tissue of the nucellus, grows gradually downward. The 
generative cell now divides into two, i. e., the so-called stalk- and 
body-cells. The process of the division itself has not been observed. 
The body-cell then assumes a more or less spherical shape, while 
the nucleus of the stalk-cell soon looses its own cytoplasm and lies 
free in the cytoplasm of the tube (fig. 27). Both the body-cell 
and the stalk-nucleus now enter into the pollen-tube, and move 
x ) The genas Phyllocladus which was formally placed in the Taxeae , 
having two or three prothallial cells in the pollen, seems to have more affinity 
to the Podocarpeae, and should better be excluded from the former (Pilger, 
1905; Robertson, 1906; Kildahl, 1908). 
