THE DEVELOPMENT OF THE EMBRYO SAC OF 
SMILACINA STELLATA 
F. McALLISTER 
(WITH PLATE XV) 
The object of this paper is to describe the development of the 
embryo sac of Smilacina stellata (L.) Desf., with a view to its pos- 
sible bearing on the current interpretations of the lily type of embryo 
sac. : 
In 1880 TrEUB and MELLINK (27) reported that in Lilium bulbi- 
ferum and in Tulipa Gesneriana the embryo sac mother cell develops 
directly into the embryo sac without any previous divisions. 
In 1884 GUIGNARD (11) and also STRASBURGER (24) called atten- 
tion to the fact of a reduction of the number of the chromosomes 
during the development of the germ cells of angiosperms. STRAS 
BURGER (25) further pointed out in 1888 that in the case of the 
embryo sac in certain orchids and in Allium, the reduction of the 
number of the chromosomes occurs in the nucleus of the embry? 
sac mother cell. 
It was further established simultaneously by OVERTON (16) and 
GurGNaRD (12) that, in the lilies and other plants in which the embry° 
sac mother cell develops directly into the embryo sac without previous 
division, reduction takes place in the nucleus of the young embry? 
sac. The natural conclusion from these discoveries is that the yours 
embryo sac in these cases is the morphological equivalent of a pollen 
or embryo sac mother cell. That the nuclei resulting from the first 
two divisions in the embryo sac of the lilies are morphological equiv 
lents of the microspores is strongly suggested by these results. 
STRASBURGER (26) in 1894, discussing the formation of the a 
sac of the lilies, concludes that the cell in which the reductio? 0. 
the chromosome number takes place is to be regarded as 4 mother 
cell and not simply as a young embryo sac, since in the ovaries ° 
Allium and Helleborus he had found that the reduction of vd 
chromosomes takes place in the embryo sac mother cell before. sags 
* Botanical Gazette, vol. 48] aa 
