368 AUTOGAMY. 



pollen must effect cross-pollination. As in so many other cases, autogamy is re- 

 served for the last moment of bloom. With a view to its ultimate achievement, the 

 two longer filaments cross themselves over the mouth of the corolla-tube in some- 

 what the same attitude as a pair of folded arms. This brings their two anthers, 

 which are still full of the orange-coloured pollen, behind the stigma. The corolla 

 now becomes detached from the receptacle and falls forward, but remains for a 

 short time suspended to the long style, where it undergoes slight torsion. Finally, 

 it drops with a gyratory motion, and as it does so the stigma must inevitably be 

 brushed by one or other of the anthers lying in front of the mouth of the flower. 

 The Pimpernel {Anagallis), which belongs to the order Primulaceae, has a corolla 

 resembling that of the Moth Mullein in being rotate and in containing five stamens 

 clothed with violet hairs. The stamens in this case are very long, and the style is 

 bent to one side, and passes between two of the stamens. Thus the stigma is out of 

 reach of the anthers, and cannot, in the first stage of the flower's development, be 

 dusted with their pollen. On the other hand, cross-fertilization may be effected by 

 the small insects wliich creep over the flat limb of the corolla in order to feed on 

 the hairs of the stamens. The flowers of the Pimpernel belong to the category of 

 those in which the corolla opens and shuts periodically. The operation of closing is 

 due to the expanded limb being thrown*into superincumbent folds. On the second 

 occasion of the flower's closing, the anthers come into contact with the part of the 

 corolla that is folded in, and leave some of their pollen sticking to it. This poUen 

 is still to be seen adhering to the inner face of the corolla on the following day, 

 when the limb expands again, and there it remains till the evening, when the 

 corolla closes for the third time. After this the corolla does not open any more, 

 but falls off still closed, and, as it does so, brushes the style, which is held between 

 two stamens, and leaves upon the stigma the pollen that was sticking to its inner 

 surface. Again, there is the case of Soldanella alpina, to which we have already 

 several times had occasion to refer in other connections, and also as affording an 

 instance of a second form of autogamy (p. 333) besides that now in question. The 

 style stands up in the form of a column in the middle of the bell-shaped corolla, and 

 has the five stamens close to it. The anthers are united into a cone, and act as 

 sprinklers in the dispersion of their pollen. When an insect pushes into a flower it 

 rubs first against the stigma, and dusts it with foreign pollen, and as it forces its 

 way further in it displaces the various parts composing the cone of anthers, and is 

 consequently besprinkled with pollen. If no insects visit the flower the anthers are 

 still full of pollen when the time comes for the corolla to drop off, and as the style 

 is drawn through the dislocated cone of anthers, the pollen in the interior of the 

 latter is caught up by the stigma, and self-fertilization is effected. 



Next to these plants, in which autogamy takes place on the fall of the corolla 

 owing to its tube slipping over the stigma, there comes a group of species in which 

 the same result is attained in the following manner. At the time when the flower 

 opens, the petals are slightly smeared with pollen, and this deposit forms a reserve 

 store. Should the stigma not have received any pollen from extraneous sources, the 



