19 
Miyake, The development of the gametophytes etc. 
The female prothallium develops, as in the other Conifers, 
at first by free cell formation in a parietal layer of protoplasm 
enclosing the central vacuole. The division of the free nnclei goes 
hand in hand with the enlargment of the protoplasmic sac. 
The wall-formation between the nuclei begins about June 
10—15. The cells then elongate toward the center, and cross- 
walls are laid down before they meet. 
The filling up of the central vacuole with prothallial tissue 
proceeds rather rapidly, and in about a week alter the first wall- 
formation the whole megasporic sac is filled with solid tissue. 
The young female prothallium is surrounded by two to f'our 
layers of tapetum-cells, whilc in the older stages the tapetum is 
rednced to a single layer of cells. In the mature prothallium, the 
tapetum shows the sign of disorganization. 
The megaspore-membrane is fairly well developed in the 
mature prothallium. and consists of two~ layers. It is thicker to- 
ward the base of the prothallium. 
The archegonia develop from peripheral cells at the micro- 
pylar end of the prothallium. They are arranged in a group, and 
the entire complex is surrounded by a single layer of sheath-cells. 
The number of archegonia in a complex yaries usually from thirteen 
to sixteen. The number of tbe neck-cells in each archegonium is 
usually four. 
The archegonial complex has a sterile prothallial tissue at 
the center and the archegonia are arranged around it completely 
enclosing the former. The archegonia are also surrounded by a 
common layer of sheath-cells. 
A ventral canal-nucleus is cut off just before fertilization. 
and it, as a rule, soon disintegrates. being usually absent in the 
mature egg. The mature egg has a large nucleus situated some- 
what above the center and a vacuole just below it. 
Fertilization occurs about the first week of July. A single 
sperm-cell enters the archegonium and its nucleus soon fuses with 
the egg-nucleus. The fusing nuclei are surrounded by a dense 
sheath of starch-granules. The outline of the female and male 
nuclei remains distinct until the fertilized nucleus prepares itself 
for division. 
The division of the fertilized nucleus takes place at or near 
the center of the egg. The two segmentation-nuclei then move 
down toward the base of the archegonium. where the succeeding 
two free nuclear divisions take place. 
Eight free nuclei arrange themselves in two tiers at the base 
of the archegonium, and the walls are then formed between thern. 
but the upper side of the upper tier is left open. The nuclei of 
the upper tier now divide. The proembryo consists of three tiers 
of cells. and the middle tier elongates into the suspensors while 
the upper tier, wliich is open above, forms a rossette, and the 
lower tier develops into the embryo. 
The gametophytes and embryogeny of Cunninglmmia shows 
a close affinity with Tcixodium and Cryptomeria , and are distinctly 
