378 Stephens. — Embryo-Sac and Embryo of certain Penaeaceae. 
Fig. 23. Upper half of embryo-sac of Fig. 21 e, with six nuclei fusing to form the primary 
endosperm nucleus. The two peripheral groups shown contain only two cells ; the remaining two 
groups are normal, x 420. Sarcocolla squa?nosa. 
PLATE XXVI. 
Fig. 24. Outline of longitudinal section through ovule at the time of fertilization, showing 
axial row of cells in nucellus. x 28. 
Fig. 25. Mature embryo-sac, showing exceptional case of division of the primary endosperm 
nucleus before fertilization, x 630. Penaea mucronata. 
Fig. 26. Embryo-sac after fertilization ; the unfertilized peripheral groups are disappearing and 
the cells of the axial row of the nucellus are breaking down, x 630. Penaea mucronata. 
Fig. 27. Embryo-sac with two-celled embryo, x 420. Penaea mucronata. 
Fig. 28. Upper part of embryo-sac with four-celled embryo, seen in optical section. The wall 
dividing the upper two cells is in the plane of the drawing : that dividing the lower two is cut 
obliquely. An empty pollen-tube is seen in the nucellus. x 390. Sarcocolla squamosa. 
Fig. 28 a. Outline of embryo-sac of Fig. 28, showing endosperm, x 28. 
Fig. 29 a, b. Sections through the same embryo-sac showing two embryos of eight cells (29 a) 
and four cells (29 b) respectively. The latter is seen in obliquely transverse optical section, being 
in a plane almost perpendicular to that of the drawing. x 333. Penaea mucronata. 
Fig. 30. Longitudinal section through embryo, showing (probably) the beginning of the 
dermatogen. x 390. Sarcocolla squamosa. 
Fig. 30 a. Outline of ovule containing embryo of Fig. 30. x 15. 
Fig. 31. Longitudinal section of embryo older than Fig. 30, with investing layer of cytoplasm 
containing endosperm nuclei, x 300. Sarcocolla squamosa. 
Fig. 32. Longitudinal section through top of embryo-sac at a later stage, showing embryo in 
median section, and dividing endosperm nuclei. The shaded cell in the centre of the embryo 
probably represents the beginning of the plerome. x 300. Sarcocolla squamosa. 
Fig. 33. Longitudinal section through top of embryo-sac at a later stage, showing embryo in 
median section (with longitudinal division of two cells in the plerome region) and formation of cell- 
walls in the endosperm, x 196. Sarcocolla formosa. 
Fig. 34. Longitudinal median section through embryo at a later stage, x 300. Sarcocolla 
squamosa. 
Fig. 35. Longitudinal section through ovule at a later stage, showing endosperm tissue and 
embryo with developing cotyledons, x 15. Sarcocolla squamosa. 
Fig. 36. Mature embryo. X 15. 
Fig. 37. Root-tip of mature embryo, x 125. Sarcocolla squamosa. 
