18 
Miyake, The development of the gametophytes etc. 
prothallial tissue in the center of the archegonial complex of 
Cunninghamia is certainly a primitive character. So far as Cunning- 
liamia is concerned, I can agree with Arnoldi in considering it 
as more primitive than other memhers of the Cupressineae so far 
investigated. 
From the presence of a steril prothallial tissue in the arche¬ 
gonial complex, I consider Cunninghamia as the most primitive 
of the three genera. Otherwise, Cunninghamia agrees with Taxo- 
dium in the essential characters of the gametophytes. Cryptomeria 
is considered as of more modern origin than the other two. as the 
tapetum of the female gametophyte seems to be less developed 
than the others. Lawson (1904) was not able to detect any ta- 
petum in Cryptomeria , but Thomson (1905) has found a poorly 
developed tapetnm around the young female prothallium. 
Summary. 
The staminate cones begin to develop in the autumn of the 
year preceding pollination. The pollen mother-cells are formed 
before the end of the year. 
The division of the pollen mother-cell takes place about the 
end of February or the beginning of March. The division shows 
clearly the stages characteristic of the reduction-division, the reduced 
number of chromosomes being. twelve. 
The mature pollen-grain contains two cells,, the larger tube- 
cell and smaller generative cell. Pollination takes place during the 
first half of April. 
As the pollen begins to send out tube, shortly after pollination, 
the generative cell divides into the body- and stalk-cells, and these 
move down toward the tube-nucleus which has previously found 
in the tube. 
The stalk-cell soon looses its own cytoplasm and its nucleus 
then passes the body-cell and lies near the tube-nucleus. 
The downward growtk of the pollen-tube is at first relatively 
slow and at the later stage it is much accelerated. The pollen- 
tube reaches the female prothallium about the end of June and 
penetrates into the depression just above the archegonial complex. 
The body-cell which is very much enlarged and almost 
spherical, now lies at the enlarged tip of the pollen-tube. It then 
divides to form two sperm-cells which are equal in size. The 
sperm-cell contains numerous starch-granules in its cytoplasm, and 
is ready to fertilize soon after its formation. 
The pistillate cones begin their development in the autumn. 
and a single megaspore mother-cell is formed in each ovule shortly 
before pollination, in the following spring. 
The megaspore mother-cell divides about the time of polli¬ 
nation. The division commences with the synapsis stage and is 
evidently the reduction-division. 
The usual number of the potential megaspores is probably 
three. One of the megaspores, the lowest of the row, develops 
into the female gametophyte. 
