238 INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



Fig. 132. Development of endosperm in Nemophila. A, N. insignis; two-cellel 

 endosperm. B, three-celled stage. C, four-celled stage resulting from transverse 

 division of middle cell. D, more advanced stage, showing small mass of cells 

 formed by divisions of two central cells; chalazal haustorium has given out a lateral 

 branch. E, l.s. ovule, diagrammatic. F, embryo sac from E, magnified to show 

 two-celled embryo, micropylar and chalazal haustoria, and central mass of endo- 

 sperm cells. G, N. aurita, diagram of l.s. ovule. //, embryo sac of G, magnified 

 to show aggressive micropylar and chalazal haustoria and central globular mass of 

 endosperm cells. (After Svensson, 1925.) 



