180 



ALLUREMENTS OF ANIMALS FOK THE DISPERSION OF POLLEN. 



but forms the principal food of humming-birds, butterflies, humble-bees, &c. 

 Of course there is again the utmost variety according to the length of the 

 proboscis or bill, and the depth of the hiding-places in which the honey is con- 

 cealed. The distance of the honey-secreting base from the restricted mouth of 

 the corolla amounts in the flowers of the Heath (Erica earned) to only a few 

 millimetres, while it reaches 16 centimetres in those of the Rubiaceous Oxyanihus 

 tubiflorus, which grows in Sierra Leone. In Angrcecum sesquipedale, a species of 

 Orchid growing in Madagascar and distinguished by the size and splendour of the 



Fig. 250. Concealment of Honey. 



1 Flower of Cynoglossum pictum, the front part of the flower cut away. 2 Flower of Linaria alpina. 8 Flower of 

 Soldanella alpina, the front part of the flower cut away. * A honey-leaf of Nigella elata. The same cut through 

 longitudinally. A honey-leaf of Nigella sativa, seen from above. The same ; the roof covering the nectar-pit cut 

 away. All the figures somewhat enlarged. 



inflorescence, the perianth possesses a hollow spur 30 centimetres long which is 

 filled with honey at its base. 



There are two kinds of contrivances for hiding the honey in pits, tubes, and 

 channels. In the one the entrance to the hiding-place is narrowed by all kinds of 

 inflations, cushions, bands, and flaps at the mouth of the flower-tube (see fig. 250 l 

 of the flower of Cynoglossum). In the other the nectary is completely closed over by 

 a roof or door, or by two lips, so that those animals which desire the honey stowed 

 away in the cavity are compelled either to raise the roof, to open the door, or to press 

 down one of the lips. As examples of the latter kind of closing may be instanced the 

 flowers of Corydalis, of the Fumitory (Fumaria), of the Snapdragon (Antirrhinum), 

 and of the Toad-flax (Linaria; see fig. 250 2 ), whilst in some Soldanellas (Soldan- 

 ella', see fig. 250 3 ), and in the genus Aechmea, belonging to the Bromeliaceae, the clo- 

 sure is effected by special scales, like folding doors, introduced into the corolla-tube. 



