288 
SVEDELIUS : LIFE-HISTORY OF 
observation at the Nicobar Islands. The currents near 
Paumben and Jaffna just where this plant lives are in fact 
very strong. According to Walther (34) the current in the 
Paumben channel often reaches a speed of 5-6 knots in an 
hour. 
The ovules are anatropous with two integuments (hg. 7). 
These are both fully developed, whereas, according to 
Müller (21), in Yallisneria the outer integument after some 
time ceases to grow, so that only half the length of the 
nucellus is provided with two integuments, and thus the 
micropyle is formed by one integument only. 
I have not been able to investigate the development of the 
embryo sac and the fertilization in my material, owing to 
the difficulty of making the fixing solution penetrate the 
copious mucilage in the young ovaries. 
In the embryo sac the antipodals are rather large. (PI. 
XXIV., A, hg. 13). Sometimes the embryo sac has a pouch¬ 
like deepening in its antipodal end, though not so large as 
in Elodea (cf. Wylie, 35). The cells of the tissue of the 
nucellus are here but little different from the rest. They 
are smaller, but their walls are thicker and stain better. 
From these smaller cells some larger ones radiate in a semi¬ 
circle, probably because they have some nutritive function in 
connection with the antipodal cells. The fertilization 
itself I have not observed, but have often seen pollen tubes 
in the micropyle. 
The young embryo has a very large suspensor cell (PI. 
XXIV., A, fig. 12) just as in Elodea (Wylie, 35). The 
embryo seems otherwise to be of the usual monocotyledonous 
type. Very few endosperm cells are formed in the embryo 
sac. Thus the embryo is suspended as if in a great 
vacuole. 
It is remarkable that during the further development of the 
embryo the integuments do not develop any more, but 
simply stretch so much that they equal the growing embryo. 
No lignification takes place in their tissue, and when the fruit 
