1915] BURLINGAME—ARAUCARIA BRASILIENSIS 7 
After the contact of egg nucleus and male cell the cytoplasm of 
the latter gradually envelops them both. Fig. 11 shows a case 
where both are completely enveloped in a common cytoplasm 
even before the nuclei have begun to fuse. In figs. 12 and 13 each 
nucleus is accompanied by a distinct cytoplasmic sheath even 
though fusion is far advanced. The egg cytoplasm is generally 
much disturbed by the passage of the male cell through it and does 
not ordinarily recover its structure. The cytoplasmic sheath 
around the fusion nucleus, on the contrary, continues to grow 
rapidly, apparently at the expense of the general cytoplasm of the 
egg. With the growth of the proembryo the egg cytoplasm grad- 
ually disappears, until there is commonly very little of it when the 
walls are formed in the former. In some cases (upper right of 
fig. 32) the mass of dense cytoplasm surrounding the proembryonic 
nuclei becomes delimited from the egg cytoplasm by a distinct 
membrane. So far as I have observed, this membrane has nothing 
whatever to do with the walls of the upper tier of the proembryo, 
which form later and entirely within the limits of this membrane. 
Fig. 31 shows a small portion of this membrane in the upper part of 
the figure, just above the largest cell shown. The left-hand cell 
shows distinctly the beginning of the formation of the walls. The 
wall is less clearly shown in the other cells, though the plasmatic 
membrane around their dense cytoplasm shows clearly where it 
will form. This membrane does not always form, and I am unable | 
to see any significance that may be attached to it. The cap of 
cytoplasm spoken of by Eames (8) as occurring above the upper 
tier of nuclei in Agathis is not ordinarily present in Araucaria, 
though fig. 27 shows a band that might be interpreted as such 
a structure. This figure also shows very clearly the previous 
delimiting membrane over the upper surface, in fact extending 
over that part of the embryo formed by the previously men- 
tioned cytoplasmic cap. No distinct membrane is to be seen in 
figs. 25, 26, and 30, even though there is sharp distinction 
between the egg cytoplasm and that of the proembryo. A mem- 
brane entirely around the proembryo is shown in figs. 28 and 29. 
The younger stages apparently do not possess membranes of 
any sort. 
