THE ENDOSPERM 237 



ber also the first two divisions are vertical, but these are followed by 

 further divisions in varying planes, resulting in a small mass of endo- 

 sperm tissue surrounding the embryo. In Crossandra, therefore, 

 the endosperm consists of only three regions: the micropylar haus- 

 torium, the chalazal haustorium, and the central endosperm tissue. 

 The genus Acanthus is more or less similar. Thunbergia, which 

 seems to differ in several respects from both Ruellia and Crossandra, 

 needs further study and will not be discussed here. 



The genus Nemophila, belonging to the Hydrophyllaceae, presents 

 an interesting mode of development. Of the two approximately 

 equal cells formed by the first division of the endosperm mother cell, 

 the lower functions directly as the chalazal haustorium (Fig. 132^1). 

 The upper divides transversely to give rise to a central cell, which 

 is responsible for the origin of the main body of the endosperm, and 

 a terminal cell, which serves as the micropylar haustorium (Fig. 

 1325). Cell divisions are confined to the central cell only, the first 

 wall being transverse and the others more or less irregular (Fig. 

 1S2C-F). The chalazal haustorium sometimes gives out a promi- 

 nent lateral branch (Fig. 132D) which grows toward the funiculus 

 and penetrates it so as to come in direct contact with the starchy 

 cells of the placenta. In one species, N. aurita, the micropylar 

 haustorium, as well as the chalazal one, becomes large and aggres- 

 sive. Fig. 132G, H, reconstructed from several sections, shows the 

 central ball-shaped mass of endosperm and conspicuous haustoria. 



Well-developed micropylar and chalazal haustoria also occur in 

 the Lobeliaceae (Hewitt, 1939; Subramanyam, 1949). In Lobelia 

 amoena (Hewitt, 1939) the first division of the endosperm mother 

 cell is transverse and the second is vertical (Fig. 133 A, B). Each 

 of the four cells now divides transversely, resulting in four tiers of 

 two cells each, i.e., eight cells in all (Fig. 133C). The two cells of 

 the micropylar tier do not divide again but extend around the zy- 

 gote, forcing their way into the micropyle and forming a large 

 haustorium; the two cells of the chalazal tier grow downward into 

 the basal end of the ovule, forming a large chalazal haustorium; and 

 the middle tiers give rise to the main body of the endosperm (Fig. 

 133 D, 22). Cross sections of the haustoria, both micropylar and 

 chalazal, show their two-celled nature quite clearly. 



An essentially similar mode of development occurs in Utricularia 

 coerulea (Kausik, 1938c) (Fig. 134 A-C). The first division of the 



