675 
Campbell. — Studies on the Araceae. 
a second cell is cut off from its base, in contact with the first 
one. In this way the formation of a solid endosperm pro- 
ceeds from the base upwards (Fig. 21) until the whole cavity 
is filled. These cells later undergo further divisions, but 
in all cases, apparently, nuclear divisions are accompanied by 
c'dl-formation. 
Not infrequently a group of cells, differing somewhat in 
appearance from the endosperm-cells, can be seen at the base 
of the embryo-sac (Figs. 27, 32). These may be possibly 
antipodal cells, but this point was not satisfactorily proven, 
and it is not impossible that in some cases, at least, they 
are merely somewhat modified endosperm cells. 
The embryo-sac shown in Fig. 23 was found in some of the 
Jamaican material referred to this species, but perhaps not 
correctly determined. In this case, as we have already stated, 
besides the egg-apparatus, there were but two nuclei, situated 
at the base of the embryo-sac, and evidently in the early 
prophases of division. A somewhat older embryo-sac (Fig. 
24), evidently of the same type, was found, and from a 
comparison with these, it appears that the endosperm forma- 
tion results directly from the further division of the two basal 
nuclei found in the younger sac. This may be a further 
development of the type shown at Fig. 9, where the three 
apical nuclei were already arranged like an egg-apparatus, 
while but a single nucleus occupied the base of the sac. The 
complete absence of antipodal cells and polar nuclei in these 
instances, and the development of endosperm without the 
preliminary nuclear fusion, is certainly noteworthy. 
The embryo-sac in Aglaone 7 na becomes strongly bent as 
it grows. The peculiar mass of cells referred to, differing 
in appearance from the endosperm-cells (Figs. 27, 32), while 
in some cases to be interpreted as a mass of antipodal cells, 
may possibly be an embryo in some instances, as unmis- 
takable young embryos have been found at the chalazal 
end of the sac ; and in some of these embryo-sacs of large size, 
and already filled with endosperm, no trace of an embryo 
can be detected at the micropylar end. 
