THE GAMETES IN PLANTS AND ANIMALS 



321 



plasm is segregated only at the last division preceding the final 

 differentiation of the egg. 



a 



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. 



