THE GAMETES IN PLANTS AND ANIMALS 



321 



plasm is segregated only at the last division preceding the final 

 differentiation of the egg. 







FIG. 141. Development of female gametophyte and formation of egg in the 

 higher seed plants: A, megaspore in the ovule; B, first division; C, second division; 

 D, third division; E, mature gametophyte: o, egg; s, synergids; a, antipodals; /, 

 primary endosperm nucleus. After Coulter, etc., '10. 



