114 THE SCOTTISH BOTANICAL REVIEW 



and with firmer walls, and might almost be compared to the 

 mass of antipodal cells found in some other Aracese. 



13. When the first division occurs in the embryo the 

 synergidae remain intact, and it sometimes looks as if they 

 also contributed to the tissues of the embryo. 



14. The embryo reaches a large size, finally completely 

 filling the embryo-sac. The development of the organs, 

 stem, leaf, and root, takes place at a late stage in the 

 development. 



1 5. The chalazal region of the ovule becomes much enlarged 

 and probably functions as a sort of perisperm, although this 

 tissue does not belong to the nucellus, which is quite obliter- 

 ated by the growth of the embryo-sac. 



It is difficult to interpret the peculiarities in the develop- 

 ment of the embryo-sac of Aglaonema. While A. pictutn 

 seems to differ very little — or perhaps sometimes not at all — 

 from the ordinary type of embryo-sac, the other species 

 examined all show a greater or less departure from this. It 

 is impossible to say whether the apparently compound 

 embryo-sac sometimes found in A. conunutatum is abnormal 

 or not, but that it may be normal is indicated by the appear- 

 ance of almost exactly the same type in Nephthytis. 



It is pretty certain that the five-nucleate sac found in A. 

 simplex and A. modestiiiii is quite normal, but as no fertilisa- 

 tion stages were found, it is quite impossible to say when the 

 embryo-sac may be said to be mature. Whether the " ^^^ 

 apparatus " is really the same as in the typical embryo-sac 

 may perhaps be questioned, as there is no degeneration of 

 the synergidae, and these may, apparently, even take part in 

 the formation of the embryo. Moreover, no evident change 

 takes place in the &^% apparatus until after the development 

 of the endosperm is well advanced. 



REFERENCES. 



(i) HoFMEiSTER, W. — Ncue Beitrage zur Kenntniss der Embryo- 

 bildung der Phanerogamen ; II., Alonocotyledonen. Leipzig, 

 1861. 



(2) Hegelmeier, F. — "Zur Entwickelungsgeschichte monocotyle- 



doner Keime." Bot. Zeit., xxxii., 1874. 



(3) MoTTiER, D. M. — " On the Development of the Embryo-sac of 



Arisama triphylhim." Bot. Gazette, xvii. 258-260, 1892. 



