256 BEES AND BEE-KEEPING. 



four nuclei resulting in each case. Mysteriously, one 

 nucleus starts from each end (pn, pn, A, Fig. 50), 

 approaches {pn, B), and at last meets, its companion 

 in the centre, and coalesces with it to form the 

 definitive nucleus (dn, C). These two nuclei are 

 called the polar nuclei. Round the two sets of 

 the three remaining nuclei a process of free cell 

 formation begins, resulting in three cells at each 

 end of the sac instead of three nuclei. Those at the 

 lower end (a, B and C) soon become surrounded 

 with cell walls, while those at the micropylar (upper) 

 extremity remain naked, and constitute the egg 

 apparatus. Two of these lie above the third, the 

 latter constituting the oosphere, or embryonal vesicle 

 (em.v), which has its nucleus lying at its lower 

 end. Generally, all three cells of the egg appa- 

 ratus position themselves in contact with the wall 

 of the embryo sac, which is, at this time, awaiting 

 fertilisation from the pollen previously placed on the 

 stigma, it may be by wind action, by the gardener, 

 or by the little professional pollen-carrier, the nature of 

 whose burden we must now endeavour to understand. 



Pollen granules vary greatly in form, colour, and 

 size. They are frequently approximately spherical, 

 sometimes oval, triangular in the fuchsia or evening 

 primrose, hexagonal in the chicory, covered with 

 minute spines in the hollyhock and aster, curiously 

 banded in the Passion flower, spirally grooved in 

 the musk ; while they are, in these and other similar 

 plants, delicately coated with an oily body, giving them 

 adhesiveness, and aiding the bee in packing them upon 

 the legs. When cut into sections, they reveal a complex 



