ArrOGAMT BY MOVESIENTS OF THE FLOWER-STALK. 379 



in a lateral direction; the stigma is stationed behind the anthers, and the pollen 

 that falls oat of the anthers does not come upon the stigmas so long as the corolla- 

 tuhe is horizontaL Dttring that period the branch of the inflorescence to which 

 the horizontality of the corolla is dne is curved, but it subsequently straightens out 

 and raises the corolla-tube to a vertical position whereby the stigma is brought 

 into the line of descent of the pollen as it falls from the shrive lling anthers. This 

 occurs in TziZi/^ci sylvestris, Polemoniura cceriUeurn, So.xifraga hie ra.cif olio., Ciiryso- 

 gpleniv/m altemifolium, PJiododeridron ChamrEcistu-s, Vacdnium, Arctostapkylo-s, 

 Ccrinthe, Symphytura, and Cyclo.rriAn. The process may be most clearly traced in 

 the various species of Cyclamen, which are at present so commonly grown in pots. 

 The first day that the flower is open and the petals reflexed, the peduncle, which 

 rises up from the ground, has its extremity bent over almost at a right angle. The 

 short bent piece of the stalk is inclined at an angle of from 50" to 60' to the 

 horizon. The variation in the size of the angle is due to the fact that the longer 

 inferior part usually ascends obliquely from the ground, and is only in rare cases 

 quite verticaL From day to day the angle of inclination may be seen to diminish 

 by about 10' until at the end of the flower's period of bloom the short down-bent 

 portion at the top and the long upright piortion of the peduncle are almost parallel, 

 and the whole has the form of a crook. As the style lies in the direct Hne of 

 prolongation of the short piece of the peduncle and projects beyond both the tube 

 of the corolla and the cone of anthers, autogamy cannot take place in the first 

 stage of the flower's development, when the style is inclined at an angle of from 

 50' to 60° to the horizon. Insects visiting the flower at this period first binish 

 against the stigma at the end of the projecting style, and may occasion cross- 

 fertilization: but even if it should happen that the displacement of the anthers 

 caused by an insect's intrusion has the eSect of letting some of the poUen fall out, 

 the shower does not descend upon the stigma, for it is not yet situated vertically 

 beneath the anthers. Towards the close of the fiowering period, on the other hand, 

 the stigma is moved by means of the inflection of the peduncle above referred to 

 into the path along which the pollen descends; the filaments become flaccid, the 

 anthers distmite, and the pollen stored in the cone is sprinkled upon the still recep- 

 tive surface of the stigma. 



This will be the best place to describe the ctirious case of autogamy which is 

 exhibited by the Calceolaria Pavonii of South America. The flowers of this plant 

 are protogynous, and when first open they are borne on almost horizontal stalks. 

 The anthers, which are still dosed, are concealed beneath the shortly truncate 

 upper-lip. The style bearing the already mature stigma is borne horizontally, its 

 tip only being bent down like a hook at a short distance from the stigma (as is 

 shown in figs. 307 ^ and 307 -} so as just to touch the roof of the inflated under-lip. 

 The short-tongued Hymenoptera which come in quest of the honey secreted 

 within the lower-lip make ttse of its roof as an aUghting-place. The instant one of 

 them settles upon it the lip drops as in the case of the .Snapdragon, the movement 

 being regulated by the powerful ribs on each side of the coroLa. The result is 



