248 INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



to show signs of degeneration. Finally, when cell formation takes 

 place in the micropylar chamber, the chalazal is almost crushed and 

 shows only a few disorganized nuclei. 



Other plants may show a fewer or a larger number of divisions in 

 the chalazal chamber. In Scheuchzcria (Stenar, 1935) it gradually 

 enlarges and becomes highly vacuolated, but the nucleus does not 

 undergo any division (Fig. 13922). An essentially similar condition 

 occurs in Echinodorus (Dahlgren, 1934a), Vallisneria (Witmer, 1937), 

 and Enalus (Kausik, 1940). In Bulbine (Stenar, 1928a) and Sagit- 

 taria (Dahlgren, 1934a) there is one division, resulting in two 

 daughter nuclei; and in Asphodelus (Stenar, 1928a) and Limnophyton 

 (Johri, 1935) there are two divisions resulting in four nuclei. On 

 the other hand, Hypoxis (Stenar, 80 1925), Ornithogalum (Schnarf, 

 1928a), Dianella (Schnarf and Wunderlich, 1939), and Zephyranthes 

 (Swamy, 1946a) show a much larger number of nuclei in the chalazal 

 chamber. In Muscari racemosum (Wunderlich, 1937) (Fig. 139F) the 

 chalazal chamber has 64 nuclei at the time when wall formation 

 commences in the micropylar. Yet another division takes place, 

 resulting in the formation of approximately 128 nuclei, which are 

 imbedded in a dense mass of cytoplasm. After this stage the nuclei 

 begin to degenerate, but the outline of the chalazal chamber remains 

 recognizable for a long time (Fig. 139(2). 



In some plants the divisions in the chalazal chamber are accom- 

 panied by wall formation and result in a small mass of cells which 

 is quite conspicuous for a time. As examples may be mentioned 

 Saxifraga granulata (Juel, 1907), Boykinia occidentalis, Mitella 

 diphylla (Dahlgren, 1930) (Fig. 140), and Lyonothamnus floribundus 

 (Juliano, 1931a). Or, the first few divisions may be free nuclear, and 

 wall formation may occur at a slightly later stage, as in Heloniopsis 

 breviscapa (Ono, 1928) and Tofieldia japonica (Ono, 1929). In 

 Narthecium asiaticum (Ono, 1929) the free nuclear divisions are 

 followed by a transverse segmentation of the chalazal chamber into 

 a few large multinucleate cells. 



In Ixiolirion montanum (Stenar, 1925) the primary endosperm 

 nucleus comes to lie laterally, although the antipodal cells, which 



80 The recent work of De Vos (1948, 1949) shows that in Hypoxis (= Ianthe) 

 the endosperm does not follow the same type of development in all species. Some 

 species such as I. schlechteri come under the Helobial type, while others like I. alba, 

 I. aquatica and 7. minuta come under the Nuclear type. 



