1 1 8 Campbell . — The Embryo-Sac of Pep eromia. 
EXPLANATION OF FIGURES IN PLATE VI. 
Illustrating Prof. Campbell’s paper on Peperomia. 
All figures refer to Peperomia pellucida , Kunth, and were drawn with the camera 
lucida, Leitz oil im. oc. i. x about 600. 
Fig. 1. Longitudinal section of an embryo-sac with sixteen nuclei, of which three 
are at the micropylar end. t , the tapetum. 
Fig. 2. An older stage, in which the egg-cell, o, is differentiated, and the 
endosperm-nuclei, E. n , are grouped together. A second large nucleus lay close 
to the egg, but there was no definite synergid. 
Fig. 3. Embryo-sac just after the entrance of one of the generative nuclei, Sp, 
into the egg-cell, o ; p. /., the empty pollen-tube. The endosperm-nuclei, E. n , are 
collected at the antipodal end of the embryo-sac. Two synergidae (?). 
Fig. 4. A. Embryo-sac just before the entrance of the pollen-tube,/, t. The two 
generative nuclei can be seen near its extremity. Three synergidae (?) ; two shown 
in B. 
Fig. 5. Fertilized embryo-sac, showing the two pro-nuclei, Sp, 0, in process of 
fusion. The endosperm-nuclei were also beginning to fuse, x , one of the accessory 
nuclei, enclosed within its cell. 
Fig. 6. A and B. Two sectioifs of an older embryo-sac, in which the cytoplasm 
fills the cavity. The two pro-nuclei were still separate. Nine endosperm-nuclei 
occupied the centre of the sac. In B is shown an unusually large accessory nucleus, 
x, enclosed in a nearly globular cell. 
Fig. 7. Beginning of the fusion of the endosperm-nuclei, E. n. Em , one- 
celled embryo, x, accessory nucleus. 
Fig. 8. Section of a ripe pollen-spore, showing the two nuclei, v and g. 
Fig. 9. Embryo-sac, shortly before the division of the fusion-nucleus, E. n. Em , 
embryo. 
Fig. 10. Embryo-sac, after the first division of the endosperm. Em , embryo ; 
the pr^-nuclei in process of fusion. 
Fig. 11. Older embryo-sac, containing a four-celled embryo, Em, and several 
endosperm-cells, x, accessory nucleus. 
Figs. 12, 13. Longitudinal sections through the integument, in., of the young 
seeds, showing the peculiar form assumed by the cells of the inner layer. The 
walls of these cells stain very strongly, but do not become noticeably thickened. 
