240 INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



D 



E 



Fig. 134. Endosperm formation in Utricularia. A, U. coerulea; l.s. ovary, showing 

 relation of ovules to the swollen placenta. B, embryo sac showing sequence of 

 wall formation in endosperm, resulting in a delimitation of the micropylar and 

 chalazal haustoria. C, l.s. seed, showing embryo and remnants of haustoria. (After 

 Kausik, 193^c.) D, U. vulgaris americana; l.s. ovule, showing the embryo e, micro- 

 pylar haustorium mh, nuclei of micropylar haustorium mn, chalazal haustorium 

 ch, integument i, and placental tissue p. E, invasion of placental tissue p by 

 micropylar haustorium mh; note the two large nuclei mn of the micropylar haus- 

 torium. F, more advanced stage, showing disappearance of cell walls of placental 

 tissue and scattering of placental nuclei pn. The more densely staining nuclei 

 mn belong to micropylar haustorium mh. (After Wylie and Yocom, 1928.) 



