254 BEES AND BEE-KEEPING. 



abundant honey- plant, removing the corolla, and making 

 a section through one of the ovaries, we find, within a 

 cavity, the ovule [ov, A, Fig. 49), which, on account 

 of its being straight instead of curved, and solitary 

 instead of one of a number, is an excellent subject 

 for study, and, for ,the present, may serve as a 

 type of those formed by flowering plants in general. 

 When examined minutely, it is observed to consist 

 almost entirely of cellular tissue — i.e., of a number 

 of minute sacs, similar to those at G (Plate VIII.), 

 placed side by side, in close juxtaposition, forming 

 («, A, Fig. 49) the nucellus of the ovule, which 

 is enveloped in two coatings of firmer texture, called 

 primine (p) and secundine (s), which grow up over 

 its surface in its early days, as shown at D. These 

 surrounding layers, however, are never continuous 

 over the apex of the ovule, where they leave an 

 open channel, called the micropyle, quite similar in 

 function to the micropyle of the egg (page 231), 

 and here permitting communication with the nucellus, 

 and a large cavity within it, called the embryo sac 

 (es). In the vast majority of plants, the two sides 

 of the ovule are unequally developed, so that, during 

 its growth, it is made to turn partly or completely 

 over, as in the anatropous ovule (E), where the 

 arrow indicates the micropylar aperture, or in the 

 ovules of Viola tricolor {ov, B), one of which is 

 shown more enlarged at F. 



The extremely interesting and instructive history 

 of the formation and development of the embryo 

 sac, with the mystic and involved movements which 

 prepare for and accompany fertilisation, can only 



