212 j BOTANICAL GAZETTE [SEPTEMBER 
Referring to the number of divisions which archesporial cells undergo 
to form the mother cell, he says: “Since we can trace the reduction 
of these divisions until, among the angiosperms, the archesporial 
cell may, without dividing, form one megaspore mother cell, it does 
not seem reasonable to suppose that the divisions of the mother cell 
to form four megaspores may not also be left out, and the mother 
cell function directly as a megaspore.” Any analogy, however, 
based upon the archesporial cell, has against it that this latter cell is 
a doubtful morphological unit. 
It cannot be maintained that any morphological interpretation yet 
proposed satisfactorily explains all the diverse types of embryo sac 
formation which have been described. That there are so many 
variations in important particulars gives ground for the expectation 
that further study may fill up many gaps in our current interpretations. 
It is plain that within the group of the Convallariaceae there ” 
types which go far toward explaining the origin of the old and familiar 
lily type of embryo sac. It is certainly plain that in Smilacina 
stellata four megaspores are formed, which are unmistakably separated 
by cell walls and subsequently recombine to form the first four nuclei 
of the embryo sac. 
All the evidence favors the view that the first four nuclei of the 
lily embryo sac are morphologically, as well as from the standpoint 
of the reduction divisions, to be interpreted as megaspore nuclei. 
SUMMARY 
1. The mother cell of Smilacina stellata divides twice to form fout 
nuclei, which are separated by walls to form four megaspores. 
2. The division walls and plasma membranes which separate me 
four nuclei are absorbed, so that the four reduction nuclei ocCUPY 
a common cell cavity. : 
3- Each of these four nuclei divides again, and the resulting eight 
nuclei organize to form the embryo sac. 
4. It is plain from these facts that we have four individual meg* 
spore cells*combining to form one embryo sac or gametophyte ™ 
Smilacina stellata. 6 
5. It is thus strongly suggested that in the embryo sac of the hie 
the first four nuclei are morphologically megaspores. 
