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: ^, megaspore in the ovule; 5, first division; C, second division; 

 D, third division; E, mature gametophyte: 0, egg; s, synergids; a, antipodals; /, 

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



