333 
Campbell . — Studies on the Araceae , 1 II. 
strongly, lay within the cavity of the embryo-sac, close to the wall. No 
preparations were found showing the fusion of the sexual nuclei, but there 
is no reason to suppose it differs from other forms that have been studied. 
Whether or not the second generative nucleus fuses with the polar 
nuclei must be left undecided for the present. If there is such a fusion 
it must occur subsequent to the union of the polar nuclei, as this takes 
place some time before the egg is ready for fertilization. 
The Endosperm. 
As in other Araceae there is no formation of free endosperm-nuclei 
in Anthnriuni , but each nuclear division is accompanied by the formation 
of a division-wall between the daughten-nuclei. The primary endosperm- 
nucleus lies at the base of the embryo-sac, and its first division occurs 
while it occupies this position, the formation of the endosperm thus pro- 
ceeding from the base to the apex of the sac, as has already been described 
for Spathicarpa and Aglaonema 1 . 
Shortly after fertilization has been effected, the antipodal cells, which 
are at no time especially conspicuous, begin to disintegrate, and before 
the endosperm formation has proceeded far, are no longer recognizable. 
Before the first division of the primary endosperm-nucleus occurs, it 
increases a good deal in size (Fig. 16). It lies close to the small antipodal 
cells and soon undergoes its first division. The earliest division stage 
encountered (Fig. 18) showed the two daughter-nuclei already completely 
separated, but the nuclear spindle was clearly evident. The chromosomes 
were still recognizable, and the nuclear membranes had not yet formed. 
No sign of a division-wall could be made out, but in a later stage (Fig. 19) 
in which the daughter-nuclei were complete, they were separated by a very 
distinct cell-wall, which cut off a small flattened cell from the base of the 
embryo-sac, just above the antipodal cells. In this case, as well as in 
a somewhat more advanced stage which was seen, the upper nucleus was 
decidedly larger than that of the lower and smaller endosperm-cell. 
The next division takes place in the upper cell and divides it trans- 
versely into two cells of nearly equal size ; in each of these cells the process 
is repeated, and a row of four large cells lying above the basal cell is 
formed. This repeated transverse division is accompanied by a con- 
siderable elongation of the embryo-sac, with but little growth in breadth 
(PI. XV, Fig. 21). 
In the lower of the two primary endosperm-cells the divisions are all 
vertical, and result in usually four cells which are decidedly different in 
appearance from the larger cells derived from the upper of the primary 
endosperm-cells, which give rise to the major part of the fully developed 
1 Campbell, loc. cit., II. 
