72 



MORPHOLOGY OF ANGIOSPERMS 



the tetrad usually formed by the microspore mother-cell. The 

 first mitosis in the megaspore mother-cell always shows the 



Fig. 28. — Trillium recurvatum. Longitudinal sections of nucellus, showing some early 

 stages in the development of the female gametophyte : x 500. .4, megaspore mother- 

 cell; nucleus shows six chromosomes, the gametophyte number. B, first division 

 of nucleus of mother-cell. C, second division of nucleus of mother-cell; mitosis 

 nearer chalaza much further advanced than that at micropylar end. D. germina- 

 tion of megaspore nearest chalaza; the other three megaspores represented only by 

 :i dense, shapeless mass. 



