Cupressineae , with special reference to Libocedrus decurrens . 297 
vacuole which forces the cytoplasm and numerous free nuclei to the peri- 
phery. The parietal layer of cytoplasm consists of a mere film in which 
the free nuclei are distributed at intervals. 
Free nuclear division now proceeds, and the amount of cytoplasm also 
increases. It is believed that the osmotic activities set up by the central 
vacuole have much to do with the absorptions of food materials from the 
surrounding nucellar tissue. 
As the amount of cytoplasm increases, free nuclear division ceases, and 
walls are formed between the nuclei. The primary prothallial cells thus 
formed are open and exposed to the sap of the vacuole on the inner side. 
The primary cells now elongate rapidly, and by their inward growth the 
space occupied by the central vacuole is eventually closed. During their 
growth numerous cross-walls are formed in the primary cells, but those on 
the inner side always remain open until the vacuole vanishes. 
A poorly developed megaspore membrane is characteristic of all the 
Cupressineae examined. 
The archegonia vary in number from six or eight to twenty-four, and 
are always grouped closely together in a single complex. There is a common 
large archegonial chamber, at the base of which the necks of the archegonia 
lie closely clustered together. A single layer of jacket-cells surrounds the 
archegonial complex. 
In none of the Cupressineae is there a ventral canal -cell formed. This 
structure is represented only by a nucleus. 
The contents of the various pollen-tubes become discharged into the 
archegonial chamber, and as the archegonia are numerous it is thus possible 
for both male cells from each pollen-tube to function. One pollen-tube 
may fertilize two separate archegonia. 
As a rule one male cell enters the egg, and its nucleus slips from its 
cytoplasm and unites with the egg-nucleus. When the sex nuclei first come 
in contact with each other the female is three or four times the size of the 
male. 
»■ 
The first spindle of the sporophyte is organized near the middle of the 
archegonium, in the same place where the fusion of the sex nuclei occurred. 
After the first division the two free nuclei of the pro-embryo become 
enveloped in a sheath of starch, and move towards the base of the arche- 
gonium. In this position they divide, and this is immediately followed by 
a third division resulting in the formation of eight free nuclei before any 
cell-walls are formed. 
The cells of the pro-embryo become arranged in three tiers — the upper 
forming the rosette, the middle tier which develops into the suspensors, and 
the group of cells at the tip which form the embryo proper. 
Considering the state of development of all the various vestigial 
structures associated with the gametophytes, and comparing them with 
