FERTILIZATION IX PLANTS 



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small quantity of cytoplasm and two centrosomes (Guignard), lying 

 near the tip of the pollen-tube (Fig. 80, A), which is developed as an 

 outgrowth from the pollen-grain and represents, with the latter, a 

 rudimentary male prothallium or sexual generation. The formation 



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Fig. 80. —Fertilization of the lily. [Guionaru.] 

 A. The tip of the pollen-tube entering the embryo-sac ; below, the ovum (ocisphere) with its 

 nucleus at ? and two centrosomes; at the tip of the pollen-tube the sperm-nucleus (cf) with two 

 centrosomes near it. B. Union of the germ-nuclei. C. Later stage of the same, showing the 

 asserted fusion of the centrosomes. R. The first cleavage- figure in the metaphase. D. Early 

 anaphase of the same; precocious division of the centrosomes. 

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