Campbell— The Embryo-Sac of Peperomia. m 
of as ‘ antipodal J cells, they must be regarded as their 
equivalents, being those nuclei which are not directly con- 
cerned in the production of the egg-apparatus or endosperm. 
The Embryo. 
The embryo remains very slightly developed, even in the 
ripe seed. The fusion of the two pro -nuclei is often not 
complete until the endosperm-nuclei have been fused. The 
fertilized egg-cell has grown somewhat and become almost 
globular. The first division is longitudinal, and is followed 
by a second longitudinal wall in each of the two cells. 
Transverse walls then form, but the embryo increases but 
little in size, nor is there much enlargement of the embryo- 
sac after the endosperm begins to develop. In Peperomia^ 
as in all the Piperaceae, the nutritive function of the endosperm 
is assumed by the perisperm, developed from the nucellar 
tissue, whose cells become filled with starch. 
The Fruit. 
The development of the fruit was not studied in detail, 
but as the writer’s observations did not agree in all respects 
with those described by Johnson, a brief note of these differ- 
ences will be given. 
From the first, the ovule completely fills the ovarian cavity, 
and finally a sort of caryopsis is formed. The innermost 
layer of cells of the ovary-wall becomes very large, and upon 
their membranes are formed conspicuous reticulate thicken- 
ings \ so that this layer forms a hard shell, covered with 
several layers of thin-walled cells. It is this inner layer of 
the carpel which constitutes the principal part of the hard 
portion of the fruit. 
The cells forming the two layers of the integument become 
very dark-coloured, but this is mainly due to a change in the 
character of the wall. They stain so strongly as to appear 
quite opaque, but in thin sections it may sometimes be seen 
1 Johnson, loc. cit, Fig. 15. 
