Campbell: The embryo-sac of Pandanus 209 



odoratissiinus several carpels are more or less completely coherent, 

 and may be compared to the compound pistils of Spa7'ganium 

 eiirycarpiim or S. Greeniu Each carpel contains a solitary anatro- 

 pous ovule attached to one side of the ovarian cavity v^ry near its 

 base. The placenta and the base of the funiculus bear thickly 

 placed glandular hairs. These are probably concerned with the 

 conduction of the pollen-tube to the micropyle. 



The ovule presents no notable peculiarities in its form. There 

 are two integuments, of which the inner one in the younger ovules 

 projects somewhat beyond the outer one, which is not very strongly 

 developed but finally reaches the lev^el of the inner integument. 

 On the inner side of the ovule the outer integument is completely 

 adherent to the funiculus (fig. 2). The embryo-sac is separated 

 from the apex oi the nucellus by several layers of cells. 



The nucellus is more or less pointed at the top, and there is a 

 very sharply defined epidermis consisting of a single layer of cells 

 except at the apex of the nucellus, where periclinal divisions 

 occur, so that there may be three or four layers of cells in this 

 region. This formation of periclinal walls, combined with an 

 elongation of the cells, produces the more or less prominent beak 

 which is usually present. Figure 3 shows a median longitudinal 

 section of one of the youngest ovules that was found. This was 



# 



the other species ex- 



amined in the form of the embryo-sac mother-cell, as well as in 

 the greater thickness of the epidermis at the apex of the nucellus. 

 As the older stages of this species w^ere not available, it is impos- 

 sible to say how they would compare with the corresponding 

 stages in the other two species that were studied. 



The embryo-sac mother-cell at this stage is undivided, but it 

 is easily recognized by its dense contents and its very conspicuous 

 nucleus. In section it appears almost triangular in form with a 

 pointed base and broad apex. Between it and the epidermis is a 

 group of cells, probably tapetal or ''parietal" cells, and, to judge 

 from the form and position of the group, they arise from the 

 division of a single cell which presumably Is a sister-cell of the 

 embryo-sac mother-cell. 



