ANIMALS AND PLANTS 251 



plantain. A familiar case of proterandiy is seen in the 

 common scarlet geranium and other species of Pelargo- 

 nium (Fig. 56, C, D). The stamens are ripe at the 

 time the flower first opens, and the pollen is shed almost 

 at once, but at this time the stigma is quite closed, and 

 the stigmatic surface cannot receive pollen. In the 

 older flowers, after the pollen is shed, the five lobes of 

 the stigma spread out widely and the stigmatic sur- 

 faces are exposed, but pollen must necessarily be brought 

 from a younger flower. 



A similar but more complicated arrangement is 

 seen in the nasturtium (Fig. 56, E, F). Like Pelargo- 

 nium there are seven stamens, which discharge their 

 pollen before the stigma is in a receptive condition. 

 The flower here is strongly zygomorphic, and the two 

 lower petals are so placed as to form a resting-place for 

 the bumblebees which are the commonest visitors to 

 the flowers. In addition to this, two of the sepals are 

 joined to form the long spur or nectary which the bee 

 must probe for the honey contained at its apex. The 

 seven stamens in a young flower are all bent downward 

 (Fig. 56, E), but as they mature they rise, one by one, 

 so that the open anther stands directly before the open- 

 ing of the spur, and any insect seeking for honey must 

 infallibly rub off some of the pollen. After all the 

 stamens have discharged their pollen they turn down 

 again, and their place is taken by the pistil, which has 

 in the meantime elongated, and the three stigmatic 

 lobes have opened and are ready to receive the pollen. 

 The open stigma now occupies exactly the same position 

 as did the open anthers, and any insect which has 

 visited a younger flower is sure to deposit upon the 



