Campbell . — Studies on the Araceae. 673 
free nuclei, apparently in process of fusion ( c ), presumably to 
form the endosperm-nucleus. 
The specimen drawn in Fig. 13 showed a group of four 
cells at the apex of the sac. Of these, two lying side by side 
( 0 , o') were hemispherical, and probably one of them was the 
egg. In contact with this group of cells was the enlarged end 
of the pollen-tube, containing a nucleus, which was probably 
one of the generative nuclei. The second generative nucleus 
was not clearly visible. Nothing resembling antipodal cells 
could be seen, but four free nuclei (Fig. 14) were seen in the 
cavity of the embryo-sac. Two of these were larger, and 
in close contact. The other two showed some indications 
of disorganization. 
Fig. 15 shows a very peculiar case, which was probably 
abnormal. There were apparently three embryo-sacs, two 
smaller ones above and the larger definitive one below. The 
two upper ones showed signs of degeneration. In the lower 
one, the chalazal end of the sac was occupied by two very 
large irregular nuclei (Fig. 16) having every appearance of 
being composed of several nuclei fused into one. Two other 
nuclei were present, one of which (Fig. 17) also looked as if it 
were compound. 
In Fig. 11 is shown a puzzling case. Separated from a 
large cell below, were two distinct cells which may have been 
derived secondarily from a division of the primary embryo- 
sac, or may perhaps represent two other embryo-sacs. There 
was no sign of degeneration in these, and with the large 
lower cell they seemed to form one structure. Traces of the 
pollen-tube could be seen, and in one of the cells two nuclei 
could be seen which were possibly the generative nuclei. 
Besides these nuclei, two others were present, and in the 
second of the upper cells there were three nuclei. In the 
lower cell were two large nuclei in close apposition. 
It is very evident that in Aglaonema commutatum we have 
to do with an extraordinarily variable plant. The not infre- 
quent increase in the number of the embryo-sac nuclei, and 
the imperfect differentiation of the usual structures of the 
