io8 Campbell. — The Embryo-Sac of Peperomia. 
Fertilization. 
Although repeated search was made, it was not possible to 
determine the fate of the second generative nucleus. One 
enters the egg directly from the pollen-tube, but what 
becomes of the other is not clear. The nuclei of the cells 
immediately surrounding the embryo-sac appear contracted 
and deeply stained in the preparation, and although in several 
cases a nucleus was seen which looked as if it might be the 
second generative nucleus, it was not possible to be certain 
whether this did not belong to one of the disorganized cells of 
the inner nucellar tissue. 
In the specimen shown in Fig. 3, the generative nucleus had 
apparently just entered the egg-cell. The nuclear membrane 
appeared indistinct, and the chromatin formed an irregular 
mass, somewhat suggestive in form of a spermatozoid ; but as 
no others were found in this stage, it must remain undecided 
at present, how far this is a normal appearance. Later, as 
Johnson has shown, the male nucleus assumes a form closely 
resembling that of the egg-nucleus, except that it is somewhat 
smaller ; but it is always decidedly larger than the generative 
nucleus of the pollen-spore (Figs. 5, 10). 
The fusion of the two nuclei does not usually occur at once, 
but there seems to be a good deal of difference in the time 
in different instances. In one case observed, the fusion of the 
nuclei was completed, and the first division of the embryo 
ensued, before any division of the endosperm took place ; but 
usually the fusion of the sexual nuclei is not accomplished 
until after the completed fusion of the endosperm nuclei. 
As usual in Angiosperms, the two sexual nuclei become 
closely appressed (Figs. 5, 10); and finally the cavities of the 
two are thrown together, and a single nucleus results. 
The Endosperm. 
As we have seen, the eight endosperm-nuclei lie close 
together, often actually in contact, and surrounded by a mass 
of cytoplasm which is much thicker than the layer lining the 
