FERTILIZATION IN PLANTS 



161 



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 



Fig. 80. Fertilization of the lily. [GUIGNARD.] 



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

 nucleus at 9 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. E. The first cleavage-figure in the metaphase. D. Early 

 anaphase of the same; precocious division of the centrosomes. 

 M 



