779 
Campbell —The Embryo-sac of Pandanus. 
sac, and differing in appearance from the other nuclei, suggests that perhaps 
the wall of an adjacent cell of the nucellus may have broken down and 
discharged the nucleus into the embryo-sac. These points, however, can 
only be settled when the history of the nuclear division is known. 
All of the cells surrounding the embryo-sac differ more or less from 
the outer tissue of the nucellus, having more watery contents and some¬ 
times rather larger nuclei; they are probably concerned to some extent 
with the nutrition of the embryo-sac, and sometimes this central mass of 
tissue suggests a mass of sporogenous cells ; and it is not impossible that 
it really may represent a mass of sporogenous tissue of which one cell only 
is functional. In Fig. 18, PI. LX, part of this tissue is shown with two 
conspicuous cells that very much resemble young embryo-sacs. 
The Embryo-sac of Pandanus odoratissimus. 
Pandanus odoratissimus was examined for comparison with P. Arto- 
carpus , from which it was found to differ only in some minor particulars. 
This species has large fruits with the carpels united into groups, forming 
more or less complete compound pistils, but the union of the carpels is 
a very loose one. The upper part of the carpel soon becomes very hard 
and woody, but the base remains succulent for some time, and is easily 
sectioned. The inflorescences from which the preparations were made were 
about six centimetres in diameter, and it was supposed that fertilization 
had already taken place. It was therefore hoped that the later stages of 
the embryo-sac could be obtained, but on examination it was found that in 
spite of the large size of the carpels, which were nearly two centimetres in 
length, the ovules were little further advanced, and not noticeably larger 
than those in the apparently much younger and smaller flowers of P, Arto- 
carpus . Pollen-spores were found on the stigma, and some of these had 
sent out their pollen-tubes. It was found, however, that the pollen-tubes 
had not yet reached the ovules. In P. odoratissimus the two micropylar 
nuclei are quite as large as those of the chalazal region, and the largest sacs 
found in this species were slightly larger than those of apparently the same 
age in P. Artocarpus. In some cases fourteen chalazal nuclei were counted, 
and occasionally a nucleus was found containing two nucleoli, looking in 
some cases as if there might have been fusion of two nuclei (see Fig. 16, 
PI. LIX, and Fig. 17, PI. LX). 
The Embryo-sac of Pandanus coronatus. 
The further study of the embryo-sac was confined to P. coronatus , as 
this was the only species secured in which the older embryo-sacs were found. 
Fig. 21, PI. LX, shows an embryo-sac of this species corresponding to 
the oldest stages found in P. Artocarpus and P. odoratissimus , which it 
closely resembles, except for its decidedly larger size and somewhat more 
