44 BOTANICAL GAZETTE [JULY 
a compact antipodal tissue, sharply distinct from the micropylar 
chamber with its free nuclei. As a consequence, the embryo sac of 
G. Gnemon has been used ever since as illustrating a female game- 
tophyte intermediate in structure between the tissue-filled sacs of 
Ephedra and Tumboa on the one hand, and the sacs of other species 
of Gnetum, which contain only free nuclei. Later the same investi- 
gator in reporting parthenogenesis in G. Ula? described the embryo 
sac of that species as being of the G. Gnemon type. 
Our material of G. Gnemon does not confirm this account. At 
an early stage of the embryo sac, eight nuclei are observed grouped 
near the center (fig. 1), the sac being invested by the loose tissue of 
the nucellus. At a somewhat later stage the nucellar cells at the 
chalazal end of the sac are strikingly differentiated (jig. 2), becoming _ 
more and more compactly arranged, gradually obliterating the 
intercellular spaces, and taking on the appearance of glandular cells. 
The relation of this tissue in its early stage to the embryo sac is 
shown in jig. 2a, As vacuolation proceeds in the sac and the free 
nuclei become parietally placed, this “pavement tissue” becomes 
more compact and extends deeper into the chalaza (figs. 3, 34). 
Still later it spreads laterally below, until it becomes fan-shaped in 
section (figs. 4, 4a), but it is always very distinct in contour and 
sharply marked off from the surrounding nucellar tissue. At the 
fertilization stage (figs. 4, 5) the sac contains only free nuclei, which 
become somewhat grouped at the antipodal end (fig. 5), but there is 
no walled tissue. Spreading below the sac, however, the mass of 
nucellar pavement tissue shows a definite contour, which might be 
merged in imagination with that of the sac and thus mistaken for 
a compact tissue within the antipodal end of the sac. Lomsy’s 
figures show the real contour of the sac, and his antipodal tissue is 
clearly this glandular pavement tissue developed in the chalaza 
So far as the sac of G. Gnemon is concerned, therefore, its fertiliza- 
tion stage is that described for other species of Gnetum. It will be 
noted that after the fertilization Stage is reached (fig. 5) the pav& 
ment tissue begins to lose its glandular character; and later it is : 
destroyed entirely by the growing endosperm. 
Lotsy, 
3 pas ee Parthenogenesis bei Gnetum Ula Brongn. Flora 92 2397-404 
bls. 9, Io. 1903. 3 
