646 Wisconsin Academy of Sciences, Arts, and Letters. 
smaller. The homoeotypic division produces four unequal 
cells, which are fully separated by plasma membranes. 
7. The plasma membrane of the first division persists while 
those of the second division quickly disappear, thus producing 
two unequal binucleate cells. 
8. The inner of these binucleate cells does not undergo any 
further growth while the outer grows rapidly and by two nu¬ 
clear divisions forms the eight nucleated embryo-sac. 
9. Certain nucellar cells in the micropylar region resist dis¬ 
integration and remain large and plump in the embryo-sac cavity 
and later divide to form adventitious embryos of which from 
one to four mature. 
10. The egg apparatus of the embryo-sac is never well de¬ 
veloped and it is practically impossible to identify the egg and 
to determine whether it also develops into an embryo. 
11. The presence of abundant pollen tubes indicates that 
fertilization occurs. 
12. Castrated flowers withered within two or three days 
showing pollination to be necessary to the development of the 
nucellar embryos. 
In conclusion I wish to express my gratitude to Prof. P. A. 
Harper for his most helpful suggestions and criticisms during 
the preparation of this paper. 
Since this paper went to press Lawson (Trans. Roy. Soc. Edinb. 47: 
661.1911.) has advanced the view based upon work on Smilacina, that 
synapsis is not due to a marked contraction of the nuclear contents 
but to a sudden enlargement of the nuclear cavity which gives the 
appearance of a contraction. Gates (Ann. Bot. 25:909.1911.) believes 
that his observations on Oenothera gigas afford evidence in favor of 
this view. 
I have ma|de camera drawings of a large number of nuclei of Smil¬ 
acina racemosa in the synaptic condition and preceding it and find 
no evidence whatever of an enlargement of the nuclear cavity at this 
period. Synapsis in this species is in every case observed a contrac¬ 
tion. 
The great number of figures of this phase published before Lawson’s 
hypothesis furnish unbiased evidence that synapsis is a contraction of 
the nuclear contents. 
