1gor } CURRENT LITERATURE 69 
oospore. In the case figured the spindle is transverse. Fertilization occurs 
while the ovules are still on the tree—CHARLES J. CHAMBERLAIN 
DOUBLE FERTILIZATION in Zea Mays, which has been suspected for 
some time, and which is believed to be the cause of xenia, is described in a 
recent paper by Guignard.* The mature pollen grain contains, besides the 
vegetative nucleus, two very small elongated male cells, each in the form of 
a slender rod, curved or straight, and the ends often pointed. The cytoplasm 
of these cells is much reduced and difficult to distinguish, and their nuclei 
appear almost homogeneous. The synergids and oosphere are large, the 
former showing near the tip a conspicuous longitudinal striation, especially in 
material fixed in absolute alcohol. The nucleus of the oosphere is very large 
and contains much chromatin, and the cytoplasm is usually highly granular 
and much massed together at the time of fertilization. Near the oosphere, 
sometimes in the median plane, sometimes near the side of the embryo sac, 
are the two polar nuclei which do not fuse before fertilization, and have 
relatively large nuclei and a small amount of chromatin. As many as a 
dozen multinucleate cells may be found in the much narrowed antipodal end 
of the embryo sac. The pollen tube, after penetrating the embryo sac, 
usually seems to discharge its contents into one of the synergids. In one 
instance the two elongated male cells were observed resting against the base 
of a synergid; under high magnification their chromatin was distinct. One 
of the male cells unites with the oosphere, the other with the polar nuclei, 
which it binds together. Fertilization proceeds with such great rapidity that 
it could be observed in very few preparations. In general, the ovules at the 
base of the ear are first fertilized, and in hybrids many ovules are not fertil- 
ized. After fertilization one of the synergids usually persists for a time, 
‘with the contents finely granular and refractive. Division of the definitive 
nucleus proceeds so rapidly that the author was not able to follow the course 
of cell division. The first two nuclei of the endosperm are large, each one 
having an enormous nucleolus and many smaller nucleoli. It is to be 
regretted that no figures are given.—W. J. G. LAND. 
THE EMBRYOLOGY of the Balanophoraceae presents many puzzling 
peculiarities. Accounts are somewhat divergent, but whether the divergence 
is due entirely to variation in the processes still remains to be seen. Writers 
agree that there is no ovule or placenta in Balanophora but that the mega- 
spore is situated in a tissue at the base of a prolongation incorrectly termed 
a “style.” Van Tieghem (1896) found that in B. zvdica the polar nuclei do 
not fuse and that fertilization occurs at the antipodal end of the sac as often 
as at the upper end. 
According to Treub (1898) in B. elongata the megaspore germinates in 
the usual manner. The polar nuclei, however, do not fuse but each divides 
2t La double fécondation dans le mais. Jour. Bot. 15:1-14. 1901. 
