388 



AUTOGAMY. 



mouth of the flower. These furrows constitute, in fact, the channels through which 

 the pollen is afterwards conducted to the stigmas. The only movements needful for 

 the attainment of this object are the inversion of the flower, and the placing of the 

 stigma in such a position that its fringed edges may reach to the furrows in ques- 

 tion. Both these conditions are complied with. The inversion of the flower is 

 brought about by a considerable elongation of the pedicel, which is very short when 

 the flower first opens, and by its semicircular inflection at the approach of night 

 and in wet weather (see fig. 31 2 2 ). The introduction of the stigmatic margins into 

 the furrows is due to the growth of the style, which carries the stigma up into the 

 conical cavity formed near the apex of the flower when the corolla-limb folds up. 



Fig. 312. Autogamy resulting from inflection of the pedicel combined with the folding up of the corolla. 



1 Gentiana Clusii showing the flower as it is when opened for the first time. 2 The same plant with its flower in the last stage 

 of development, the corolla closed and the pedicel elongated and curved downward in a semicircle. 3 Longitudinal 

 section through a newly-opened flower. * Longitudinal section through a flower which has closed for the last time. 



All the furrows of the corolla-tube open into this cavity, and converge into such 

 proximity to the axis of the flower that contact with the edges of the stigmatic 

 lobes, which occupy the middle of the conical cavity, is inevitable. If, under these 

 conditions, the drooping flower is shaken by drops of rain falling upon it, or by 

 gusts of wind, the pollen slips along the smooth furrow right down to the stigma, 

 and is caught by its fringed margins (see fig. 31 2 4 ). It is worthy of note that 

 Gentiana acaulis, G. angustifolia, and G. Clusii the plants to which the above 

 description applies grow for the most part on grassy slopes, and on the ledges of 

 precipitous rock-faces in the Alps; thousands of flowers of these species may be 

 seen in situations of the kind with their heads drooping in wet weather so as to lie 

 parallel to the slope of the ground, and fruits are invariably developed from these 

 flowers, even after long-continued rain. On the other hand, flowers growing on flat 



