Elementary Biology 



age through it of the male protoplasm. The pollen tube 

 fixes itself to the two upper cells of the rudimentary ovarium, 

 and seems to become continuous with their substance. The 

 nucleus of the male reproductive cell, which has meanwhile 

 migrated down the pollen tube, becomes dissolved in the 

 general protoplasm, and apparently in that form penetrates 

 the endosporium and enters into the two upper cells, which 



FIG. 87. FERTILISATION. (Vines.) 



o- 



A, B, and C, succes-ive stages in ihe fusion of the male and female pro- 

 nuclei : pt, pollen tube ; ;/, male pronucleus ;.//, female pronucleus ; 

 o, ovum. 



are frequently spoken of as the synergidse. These in turn 

 fuse with the ovum, which thus has transferred to it some of 

 the male fertilising matter. The nucleus (of the reproductive 

 cell of the pollen grain) reaggregates and appears in the 

 ovum, with the nucleus of which it fuses, completing the act 

 of fertilisation. The pollen tube now withers away and the 

 synergidae disappear. 



Results of fertilisation. The first result of fertilisation 

 is the assumption by the fertilised ovum or embryo of a 



