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



and similar ones are developed later in the axils of all the 

 other leaves. The stem-apex at this time projects strongly 

 and shows the same arrangement of cells as in the mature 

 plant (fig. 74). 



All the cells of the embryo contain starch in large quan- 

 tities, and the nuclei are very distinct and rich in chromatin. 

 The walls of the superficial cells are rather thick, and, 

 perhaps, cuticularized, and it is quite possible that the em- 

 bryo is mainly nourished through the enormously enlarged 

 suspensor cell, where the thick, granular cytoplasm and large 

 nucleus suggest that it is actively concerned in the elabora- 

 tion of food for the growth of the embryo. 



XI. The Endosperm. 



The actual fusion of the two polar nuclei to form the pri- 

 mary endosperm nucleus was not seen, although in one or 

 two instances they were found in close contact (fig. 50), 

 apparently in process of fusion; and in only a few in- 

 stances was a single endosperm nucleus observed. So gen- 

 erally were the polar nuclei separate, that the possibility of 

 there being no fusion suggested itself. However, this lat- 

 ter is merely a suggestion which was not proved. A peculi- 

 arity noted, which was also observed in Zannichellia, was the 

 presence of a single large nucleus close to the antipodals, 

 which was conspicuous at an early period and behaved much 

 like the nucleus of the suspensor. Whether this was the lower 

 polar nucleus or one of the two endosperm nuclei resulting 

 from the first division of the primary endosperm nucleus, 

 could not be determined. Whichever is the case, it never 

 divides, and all the endosperm nuclei arise from the division 

 of the other primary endosperm (or polar?) nucleus. The 

 development of the endosperm is limited, there being usually 

 no trace of cell formation. The endosperm nuclei are dis- 

 tinct, with a well marked nucleolus, and are embedded in the 

 granular cytoplasm lining the wall of the embryo-sac, and 

 especially in that immediately about the young embryo (fig. 

 64, k'). In the later stages they present quite a different 



