The Ovule of the Bruniacese 
29 
Unfortunately, no later stage than this was obtained in Audouinia, but 
there is every indication that the mature structure would be similar to the 
other three genera. In these the further development results in the more 
or less complete absorption of the nucellus. The amount of nucellar 
tissue I which remains in the mature ovule at the base of the embryo-sac 
seems to vary inversely with the number of ovules in the ovary. In 
Berzelia (one ovule) a considerable proportion of the base of the nucellus 
remains (Fig. 4), in Staavia (2 ovules) a very small part remains (Fig. 5), 
whereas in Brunia (4 ovules) the whole of the nucellus disappears 
(Figs. 6, 7, 8). 
The nuclear structure of the mature sac is perfectly normal : 2 pyri- 
form synergids, a spherical egg cell, 2 polar nuclei, fusing before 
