THE MORPHOLOGY AND AFFINITIES OF GNETUM 1 63 
The conspicuous fusion nucleus is relatively very large and is 
situated in the center of a large cell. It is quite impossible to distin- 
guish the male and female chromosomes. In view of the independence 
of the maternal and paternal chromosomes until after the first di- 
vision in many recently described cases, I have examined this phase 
of the life history very carefully but have always found that the two 
nuclear masses become quite indistinguishable and that later a single 
large nucleolus is formed. The cell containing the fusion nucleus is 
usually in contact with the old pollen tube. Sometimes the embryo- 
sac in which it is found is nearly filled with cellular endosperm; some- 
times it contains many free nuclei. 
In G. gnemon the sexual cells are not surrounded by a cellular 
endosperm. The cell containing them is, however, surrounded by a 
more or less definite mass of cytoplasm with many free nuclei. It is 
usually found either against the end of the pollen tube or the wall of 
the embryo-sac. I have not seen the actual fusion of sexual nuclei 
in G. gnemon and consequently cannot state exactly when it takes 
place with respect to the formation of this protoplasmic mass. Figure 
53 represents the whole sac at this time and figure 54 the fertilized 
egg surrounded by the body of protoplasm and nuclei. 
The possibility of the occurrence of typical ''double fertilization" 
will be discussed in connection with the endosperm. But I wish to 
recall at this point Lotsy's (19) statement that both male cells function 
in the production of embryos, or, in other words, that twice the num- 
ber of embryos are formed as there are entering pollen tubes. While 
this may be the case occasionally in G. gnemon, my sections show 
that in the great majority of cases only one functions as is usual. 
In most cases one fertilized egg only is found in a sac. Lotsy was 
probably led into error by the number of suspensors which are produced 
by a fertilized egg (page 44). The only evidence I have found in 
favor of Lotsy's statement is one case in which two fertilized eggs 
were present, although only one tube had apparently entered the sac. 
Whatever be the conditions in G. gnemon, certainly only one male 
cell usually functions in other species. I have often seen both male 
nuclei in a compartment with an egg and obviously the one which 
would not fertilize this egg could not fertilize any other. 
