March, 1907.] The Embryology of Sagittaria lancifolia. 
99 
nucleus but advanced the idea that it might “play an important 
part in the transfer of food material from the funicular region, 
beyond the antipodals, to the cotyledons, and especially in 
facilitating the formation of the cap of endosperm which covers 
the tip of the cotyledon.” This idea has been supported by my 
papers on the Nymphoeacece* in which I found similar structures 
and by Ikedaf, who demonstrated the antipodals to be in the 
course of the food supply in certain species of Liliacece. In 5. 
lancifolia I find further evidence in favor of this view; in many 
instances the antipodals disappear and this part of the sac is 
extended into a pocket-like structure (Fig. 3) in which we find a 
mass of protoplasm extending to the lower endosperm cell. At 
this time the embryo (Fig. 17) was well advanced. 
Embryo. 
Although the author did not secure the very youngest stages 
of the embryo, after examining a large number, it seemed evi¬ 
dent that the embryo had followed exactly the same line of 
development as the embryo of S. variabilis. The elongation of 
the embryo was due to the repeated division of the cell next to 
the suspensor. By the time four cells in addition to the large 
suspensor cell had been formed, the apical cell divided by the 
formation of a longitudinal wall (Figs. 5, 6). After this the 
longitudinal divisions were found to be somewhat irregular 
(Figs. 7 to 1G). The longitudinal cell walls w’ere frequently very 
indistinct but the number of cells could be ascertained by count¬ 
ing the nuclei of the serial sections. My material was unsatis¬ 
factory for making a study of the more advanced stages of the 
embryo but it apparently followed the same course of develop¬ 
ment as S. variabilis. 
From the facts herein presented it appears that the internal 
and external characters do not necessarily co-ordinate. In the 
case of Nymphcea advena of the north and the Nymphcea - 
of Cuba which so far as external characters are concerned are 
strikingly similar the embryos show considerable differences, 
while in the case of S. variabilis and S. lancifolia the external 
characters are strikingly different and the embryological char¬ 
acters are practically the same. But we are now confronted by a 
new question which can only be answered by future investiga¬ 
tions: Are the embryological characters of the plant more or less 
plastic than the external characters? 
* The development of the Embrvo-sacs and Embryos of Castalia 
odorata and Nymphaea advena. Bull. Torr. Bot. Club. 24: 211-220. 
t Ikeda, T.—Studies in the Physiological Functions of the antipodals 
and Related Phenomena of Fertilization in Liliaceae. I. Trycirtis hirta 
Bull. Coll. Agri. Tokyo Imp. University. 5: 41-72. 1902. 
