382 BOTANICAL GAZETTE [NOVEMBER 
seems very evident that this nucellar tube and its nucleus, which has 
common origin with the endosperm nuclei, are important structures for 
supplying food to the embryo through the agency of the endosperm. 
In Castalia pubescens, where the tube is developed, the same function 
is performed, first by the axial core of elongated cells (fig. 24) and 
later by the small nucellar tube (fig. 9). 
YorK (28) in his studies on Nelumbo did not observe the forma- 
tion of a nucellar tube with its nucleus, but claims that both nuclei 
formed by the first division of the primary endosperm nucleus divided 
repeatedly. However, it may be that York failed to observe the 
first division of this endosperm nucleus, that the tube nucleus dis- 
integrates very quickly as in Castalia pubescens, and that he really 
observed the secondary divisions of the daughter endosperm nucleus 
in the micropylar end of the sac. 
ENDOSPERM, 
The development of the endosperm in this family presents two 
distinct types, Nymphaea, Castalia, and Nelumbo illustrating one, 
and Brasenia and Cabomba the other. The first type shows the 
formation of cell walls, that is, a cellular endosperm throughout its 
entire development; while the second type forms cell walls only in 
the latter part of its development. The formation of the two types 
of endosperm by closely related plants has been noted by several 
investigators. 
In the first type the first cell walls are formed across the sac 
(figs. 13a, 20, 23), but gradually become more irregular and extend 
in various planes (figs. 21, 24, 25). At first the cells contain eee 
siderable protoplasm and the entire endosperm is very active, but in 
a short time it seems to have reached its maximum activity and 
importance. In Castalia pubescens, at about the time and following 
the appearance of the cotyledonary ridge, the endosperm cells imme- 
diately over the plumule show a marked difference from the sur- 
rounding cells (fig. ga,x). They are slightly smaller, more delicate, 
and are probably the cells which give nourishment directly to the 
embryo. In this same species the endosperm may penetrate the 
antipodal end of the nucellar tube a short distance (jig. 23): 
In the second type, represented by Brasenia and Cabomba, the 
