THE ANGIOSPERMAE 



1087 



possibly by the action of the synergidae. Meanwhile the tube nucleus 

 disappears and the male gametes enter the embryo sac. One of them moves 

 to the oosphere, the other joins the two polar nuclei. Nuclear fusion then 

 takes place in each case, one male gamete fusing with the oosphere and the 

 second male gamete with the two polar nuclei. During the first division 

 of the fused nuclei the different sets of chromosomes are intermingled and 

 fertilization is complete. There is thus a double fertilization of the 







Fig. 1056. — Longitudinal section of the ovule of Aqiii- 

 legia. The chalaza is above, the micropyle below. On 

 the right is the funicle with a young vascular bundle. 

 In the middle is the dark-coloured nucellus containing 

 the \ery large embryo sac, in which may be seen one 

 antipodal, the two polar nuclei and portions of two 

 synergidae. The oosphere nucleus is not in the sec- 

 tion. The two integuments can be distinguished at 

 the micropyle end. The whole ovule is anatropous. 



oosphere and of the polar nuclei respectively, the latter also constituting 

 a triple fusion. From the fertilized oosphere there develops the embryo, 

 and from the triple polar nucleus develops the endosperm, or nutritive 

 tissue, which however is sometimes abortive. During the post-ferti- 

 hzation developments the nucellus usually shrivels and the integuments 



