FERTILIZATION 



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protoplasm than the other cells. It divides, and, in the division, 

 reduces the number of chromosomes by one half. There are a 

 number of complicated divisions that follow. Ultimately, an egg 



rmlnating 



cmfhen/ 



<fil(nnent/- 



ovule 





A. longitudinal section of a pistil shows pollen grains germinating through the pistil in the form 

 of tubes. One tube is shown penetrating the micropyle of the ovule. The pollen tubes carries 

 the sperm cells to the embryo sac of the ovule. 



nucleus and two polar nuclei are produced among other nuclei 

 found in the embryo sac. The ^gg nucleus with its reduced 

 number of chromosomes is the female gamete of the plant. 



Fertilization. Wlien the end of the pollen tube gets to the 

 embryo sac, the wall of the pollen tube and the wall of the 

 embryo sac are dissolved and one of the two sperm nuclei unites 

 with the egg cell nucleus. The two polar nuclei fuse and the 

 second sperm nucleus sometimes unites with them . This completes 



