AUTOGAMY BY A CO-OPERATION OF MOVEMENTS. 



383 



the stifF upright stem (see fig. 309 ^). The pedicels are thickened just where they 

 pass into the flowers and bent down so as to hold the flowers, when they are newly 

 open, approximately at right angles to their stalks, which gives a curious appearance 

 to the inflorescence as a whole. The flowers are protogynous, and, on the first day 

 that they are open, the stigma can only be dusted with extraneous pollen from older 

 flowers. The style is originally curved, so that the receptive tissue is held in front 

 of the entrance to the floral interior where honey is abundantly secreted, and in 

 this position it is inevitably brushed against by insects visiting the flower (fig. 309 \ 



Fig. 30S.— Autogamy caused by the combined inflections of pedicel and stamen-fllaments: Pyrola uniflora. 



1 Longitudinal section through a bud about to open. 2 The whole plant with its flower in the first stage of development. 

 3 Flower in the first stage of development slightly magnified ; the front petals are cut away. * The entire plant with its 

 flower in the last stage of development, s Longitudinal section of a flower in the last stage of development ; slightly 

 maguifled. 



the right-hand flower). The next day the style straightens out, and the stigma is 

 consequently moved away from the passage to the honey, whilst, on the other hand, 

 the anthers open and place their pollen-coated faces exactly in the path of insects 

 coming in search of honey (fig. 309 \ the middle flower). On the third day the style 

 becomes curved again and takes up the same position as it occupied on the first day. 

 At the same time the pedicel undergoes further inflection and brings the tubular 

 corolla nearer to the main axis of the inflorescence (fig. 309 \ the left-hand flower). 

 The result of these combined inflections is that the viscid stigma is brought right 

 under the anthers at the time when they are shrivelling and catches a portion of 



