326 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



EXPLANATION OF PLATE XLVIL 

 Figs. 33-36 refer to 5". Greenii, the others to S. simplex. 



Fig. 24. Apex of fertilized embryo-sac with one-celled embryo. Oc. i, 



im. yV- 

 Fig. 25. An embryo of the same age, but with a broader base of attachment. 



One synergid could be still made out. 

 Fig. 26. A recently fertilized embryo-sac; one of the enlarged antipodals, 



atit., is shown. Tiie endosperm-nucleus has divided once. Oc. 



I, obj. 7. 

 Fig. 27. The antipodal region of the same more highly magnified; the three 



enlarged antipodal cells lie in the same plane; one of the two 



endosperm-nuclei is shown. 

 Fig. 28. Enlarged antipodal cells from an older sac; each of the cells shown 



has two nuclei; the whole number of nuclei was eight or nine. 



Oc. I, im. T^j. 

 Fig. 29. Two sections of the antipodal group from a still older sac; some of 



the nuclei are dividing; twelve antipodal nuclei could be distin- 

 guished. Oc. I, im. yV- 

 Fig. 30. Nearly median section of the antipodal group from a much older 



sac. Oc. I, obj. 7. Divisions have formed between all the 



nuclei; numerous free endosperm-nuclei, e>i., are present. 

 Part of the lining layer of protoplasm with a single endosperm- 

 nucleus. Oc. I, im. jV- 

 Surface view of a portion of the nucleated protoplasmic layer lining 



the wall of the embryo-sac. 

 Antipodal cells from the unfertilized sac of 5. Greenii. Oc. i, 



im. tV. 

 Antipodal group shortly after fertilization; the upper cell has en- 

 larged and divided; the two lower ones show indications of 



disintegration. 

 Antipodal group of 5". Greenii in which all the cells appear active. 

 A somewhat older group of the same species; growth is mainly 



confined to the upper cell. 

 Fig. 37. Upper end of embryo-sac of 5". simplex showing the young embryo 



surrounded by the endosperm-cells; the central nuclei, en, are 



still free. Oc. i, obj. 7. 

 Fig. 38. The embryo from fig. 37 more enlarged. 

 Fig. 39. Median section of a similar embr>'o. Oc. i, im. -^^\ xx, the basal 



wall. 

 Fig. 40. Series of three cross-sections of an embryo of about the same age; 



a, the lowest segment. 

 Fig. 41. Two sections of an older embryo, cut in the plane of the cotyledon. 



Oc. I, obj. 7. 

 Figs. 42, 43. Longitudinal sections cut at right angles to the plane of the 



cotyledon; the basal wall is decidedly oblique. Oc. i, obj. 7. 

 Fig. 44. Three cross-sections of an embryo of about the same age as 42; the 



lowest segment is divided into four cells. Oc. i, obj. 7. 

 Fig. 45. Upper part of embryo-sac showing the embryo surrounded by the 



densely granular endosperm-cells; the granular cell-contents of 



the embryo are not shown. Oc. i, obj. 7. 

 Fig. 46. The same embryo shown in fig. 45, showing the differentiation of 



the primary tissues, the plerome ends at the basal wall, xx. 

 Fig. 47. A transverse section of an embryo of about the same age. Oc. i, 



obj. 7. 

 Fig. 48. Section in the plane of the cotyledon of a similar embryo, with very 



regular arrangement of the tissues. Oc. i, obj. 7. 

 Fig. 49. Median section of an older embryo, showing the stem-groove, st. 



Oc. I, obj. 7. 

 Fig. 50. Embryo of about the same age, cut in the plane of the cotyledon. 

 Fig. 51. Median section of the base of the same embryo, more highly mag- 

 nified; pi., the plerome. 



