404 BOTANICAL GAZETTE [JUNE 
elongating it to keep pace with the development of the integu- 
ment. The result is shown in fig. 6. The line of union between 
the integument and the sporophyll proper is clearly indicated. In 
being attached along the entire side to the sporophyll, the ovule of 
Araucaria presents a sharp contrast to that of Agathis, which is 
attached only at the base (6). | 
In the nucellus three regions are at this time distinguishable. 
The tip consists of large clear cells, more or less isodiametric. Below 
this region the cells are elongated in the direction of the axis of the 
nucellus and arranged in fairly distinct rows. The rows become 
less definite toward the base. In the central portion of the base 
of the nucellus lies a group of cells with larger nuclei and denser 
contents. The megaspore arises in the midst of this group. This 
probably corresponds to the spongy tissue of various conifers, 
though it does not behave in precisely the same way during the 
further development of the ovule. Further reference to it will be 
made below. 
The megaspore is picked out in a position above the bottom of 
the cleft between nucellus and integument. As it lies within the 
meristematic zone of the former, it follows that in the further 
growth of the ovule the female gametophyte will lie almost exclu- 
sively above the bottom of this same cleft. In this growth the 
nucellus does not enlarge its tip greatly. The result is that by the 
time the archegonia are ready for fertilization the nucellus is com- 
posed of a swollen base, containing the gametophyte, and a small 
extension above. The ovule at this time measures about 1 cm. 
in length and 3-4 mm. in diameter. The gametophyte extends 
through about half of it, and is about 1.5 mm. in diameter. It is 
somewhat oval in outline, with the archegonial end noticeably 
broader (fig. 4). The micropyle is shaped something like a human 
mouth, with its longer diameter transverse. Sometimes the upper 
lip is split back into a wide and deep V-shaped cleft extend- 
ing back half the length of the gametophyte. Occasionally the 
latter breaks through the tissues of the nucellus and is openly 
exposed in the region of the archegonia. The further growth of 
the ovule gradually transforms the whole structure of ovule and 
sporophyll into the seed. The changes involved will be discussed 
