22 



INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



developed. In the ovules the megaspore mother cell develops di- 

 rectly into the embryo sac without any reduction in the chromosome 

 number and the diploid egg produces an embryo without fertiliza- 

 tion (Fig. 21). Murbeck similarly showed that some species of 



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Fig. 21. Apomixis in Antennaria alpina. A, mature embryo sac. B, later 

 stage, showing enlargement of egg and increase in number of antipodal cells; polar 

 nuclei preparing to divide. C, embryo two-celled; polar nuclei in division. (Re- 

 drawn after Juel, 1900.) 



