62 



ORGANOGEAPHY AND GLOSSOLOGY. 



in the hollow spur of the petal. In the Pine (fig. 342), the anther is tipped by a 

 bract-like connective. In Thuja (fig. 348), the filament bears a lateral three- 

 celled anther, above which it dilates into a peltate disk. In the Cypress (fig. 344), 

 the arrangement is the same, but the anther is four-celled. The anther is basifixed 

 (a. lasifixa), when attached to the filament by its base [Wallflower, fig. 11; Tulip, fig. 

 345) ; — suspended [a. apicifixa), when attached by its top {Vitex, fig. 346 ; Lamium, 

 fig. 347) ; in this case the cells often diverge, their tops touch, and it becomes 

 difficult to decide whether they are two-celled ; — dorsifixed [a. dorsifixa), when 

 attached by the back [Myrtle, fig. 348) ; — versatile [a. versatilis), when it rocks upon 

 its filament, which in this case is not confluent with the connective, but attached to 

 it by a finely pointed end [Lily, Colchicum, fig. 349). 



The anther is introrse [a. introrsa), when the sutures are turned towards the 

 centre of the flower [Campanula, fig. 319 ; Thistle, fig. 316 ; Heartsease, fig. 341) ; — 

 extrorse [a. extrorsa), when the sutures are turned towards the circumference of the 

 flower [Iris, Ranunculus, Hepatica, fig. 332) ; in these two cases the valves of each 

 cell are unequal. The sutures are lateral when the valves are equal [Myrtle, fig. 34S). 

 Dehiscence. — The dehiscence, or separation of the 

 valves of each cell, may be vertical or longitudinal [a. 

 longitudinalis), and either from top to bottom, or the 

 reverse [Wallflower, fig. 11 ; Campanula, fig. 319) ; — or 

 transverse [a. transversa), when it is horizontal, which 

 principally occurs in unilocular anthers [Alchemilla, fig. 

 328) ; — or apical by pores or slits [a. apice dchiscens), in 

 ItameJf^m^')!' Nightshade (fig. 350), when the sutures open above only ; — 

 or valvate [a. valvula dehiscens), when one valve of a cell 

 comes away in one piece ; in Berheris (fig. 351) the posterior valve dehisces near 

 the connective, and ascends elastically like a trap ; in Laurel the anterior valve does 

 this ; in some Laurels with a four-celled anther, the dehiscence is by four such valves. 



Pollen. — Pollen varies in different plants, but is always alike in 

 species ; ' its grains are commonly ellipsoid (fig. 357) or spheroid (fig. 

 sometimes polyhedral or triangular [CEnothera, fig. 353) ; their surface 

 is smooth, rugged, spinous [Rose-mallow, fig. 352), or reticulate, &c. 



The ripe pollen-grain generally consists of two membranes, the 

 inner lining the outer, and containing a thick granular liquid, often 

 vvv;-r>'v mixed with minute oU-globules ; this liquid, called the 

 ^~!r!j^ fovilla, is the essential part of the pollen. 



The structure of the pollen-grains may be easily 



the same 

 352), but 



^^'yjj_'j^{f/' observed when they are moistened, which causes them to 



SM. Eose-mauow. burst, from the inner membrane expanding more than 

 Adult pollen. ^-^^ outcr, and rupturing the latter. At certain points of 

 its surface the outer membrane is thinner than elsewhere, and there folded inwards, 

 or it presents dots which are regarded as pores. In most cases the membrane s^vells • 

 at these points the fold disappears, the dots or pores enlarge, and the outer 

 membrane bursts at the thin part ; the inner membrane, thus set free, emerges from 



' To this there are many exceptions. — Ed. 



