AUTOGAMY BY ELONGATION OF PISTIL. 



349 



that may happen to be brought by insects to be transferred to the stigma, owing to 

 the anthers forming a hood over it. At this stage every other object is subordinated 

 to the dispersion, through the agency of insects, of the pollen exposed by the flower. 

 After the interval of another day the observer finds a third aspect of the flower pre- 

 sented to him. The filaments have straightened themselves out, and so brought the 

 anthers nearer to the stigma; the coating of pollen has spread all over the anthers. 



Fig. 298.— Autogamy brought about by elongation of the pistil. 



^, "^j 3 F'luwer of EpiTnedium alpinum at successive stages of development, showing primary adaptation to cross-fertilization 

 and subsequent adaptation to self-fertilization. * Front view of a closed anther. & gi^ie view of the same. The front 

 (right-hand) wall of each of the two loculi has become detached and been raised up as a flap or valve. 6 The same anther; 

 the flap has curled up more tightly and now forms a sort of cowl arching over the spear-like apex, i, 2^ a x 10 ; ^,^,^ x25. 



and the ovary has undergone elongation, carrying the stigma into the midst of the 

 dome of anthers, where it becomes thickly overlaid with pollen 



Again, in the nodding fiowers of Atragene alpina, and in these of Clematis 

 integrifolia, which grows freely in the swampy meadows of the Hungarian plains, 

 we find autogamy effected by means of an advance of the pistil into proximity to 

 the anthers laden with pollen. Both plants are protogynous — the stigmas being 

 mature for a short time before the anthers dehisce — and in both the newly-opened 



