u 



AUTOGAMY AIDED BY THE COROLLA. 377 



stage bends down so sharply as to look as if the flower had been wilfully broken. 

 The back of the upper lip, which originally constituted a direct prolongation of the 

 corolla-tube, now forms with it an angle of 60°, and later an angle of 90°. I'he 

 movement is shared, of course, by the style and by the tongs-like stamens concealed 

 beneath the upper lip. The consequence is that the stigma at the end of the style is 

 no longer in front of the anthers, but underneath them, and that the anthers, which 

 hitherto have been held tightly together, move asunder and let their pollen fall. The 

 stigma is situated in the line of descent of the pollen, and, being very viscid, it catches 

 a quantity of the particles of the shower, and thus secures the accomplishment of 

 autogamy (c/. fig. 276, p. 272). The same changes of position, which, spontaneously 

 initiated at the close of the flowering period lead to autogamy, may, curiously 

 enough, be brought about at an earlier stage by the humble-bees which fasten on to 

 the flower, but in that case they result in cross- and not self-fertilization. For a 

 description of the processes involved the reader is referred to the account of them 

 given on p. 272, where Pedicularis recutita is the species dealt with. We may here 

 remark that the whole of the pollen which falls from the anthers in the last stage 

 of flowering is not devoted to autogamy; the few pollen-cells which stick to the 

 viscid stigma are sufiicient for that purpose. A larger number of pollen-cells fall 

 past the stigma into the air, where they may be caught up by a gust of wind, and 

 carried away in the form of a tiny cloud of dust. If mature stigmas of other 

 fedieularis-Howers happen to lie in the direction in which the dust-cloud travels, 

 individual cells of the cloud are left behind on these stigmas, and cross-fertilization 

 thus ensues in the same way as in the flowers of the Toothwort (see p. 330). 



Of the Khinanthaceas most nearly allied to the genus Pedicularis a few species 

 of the Cow-wheat, which may be represented bj' Melampyrum, sylvaticum, remain 

 to be mentioned as instances of plants exhibiting the form of adaptation above 

 described. The sole difference is that in Melamj^yrum sylvaticum the tube of the 

 corolla bends at a sharp angle at a point only 2 mm. above the base, whilst the limb 

 itself, composed of the lips, undei'goes no independent flection. The result is the 

 same as in those species of Pedicularis of which an account has been given, inas- 

 much as the pollen falls, in consequence of the inflection, from the anthers of 

 stamens of the sugar-tongs type on to the stigma beneath. 



A kindred process to the preceding consists in the anthers with their coating of 

 pollen being brought into contact with the stigma by means of an inflection of the 

 corolla. The pollen is not mealy in this case, but adhesive. No one who will take 

 the trouble to examine the inflorescence in one of the twining species of Honeysuckle 

 (Lonicera Ga2mfolium, L. Etrusca, or L. Periclymenum) can fail to notice that 

 the corolla-tube, in buds which are about to open, ascends in an oblique direction, 

 that in newly-opened flowers it is horizontal, and that, a short time before a flower 

 fades, it is bent downwards. The angle through which the axis of the flower is 

 displaced relatively to the flowering stem varies from 45° to 90°; in the case of 

 horizontal stems it is less, and in that of erect stems greater, but the object invari- 

 ably aimed at is that the open corolla shall, as night comes on, be disposed in 



