168 



ALLUREMENTS OF ANIMALS FOR THE DISPERSION OF POLLEN. 



.„^^T"V 



which are sometimes found united into a thick fur, sometimes arranged in regular 

 rows or bands, or grouped into brushes. Some of the hairs are soft and flexible, like 

 delicate little feathers, and when these structures are crowded close together, they 

 act just like a dusting-brush. The pollen over which they have swept, and with 

 which they have become covered, remains hanging between the feathers, from which 

 it can easily be removed afterwards. Other hairs, as already mentioned, are short 

 and stiff, and resemble eyelashes or bristles, arranging themselves in regular rows, 

 so as to form small besoms. In bees and humble-bees these brushes occur on the 

 end-segments of both hind-legs, while in species of Osmia only a single brush is 

 formed on the lower side of the abdomen. When these insects stroke the pollen- 

 covered anthers, or the petals on which the loose pollen has fallen, with their legs 



or abdomen, they remove the pollen with the 

 small brushes and the chinks between the 

 bristles are quite filled with it. Moreover, 

 the bees and humble-bees, with the assistance 

 of the brushes on the terminal segments of 

 their hind-legs, are able to comb and sweep 

 off the pollen which was imprisoned in the 

 soft hairs of their own fur, and thus these 

 brushes form excellent collecting apparatus. 

 In addition, these insects have special contri- 

 vances on their legs which have been com- 

 pared to little baskets ; they are smooth, 

 sharply-defined hollows, hedged in by stiff 

 rod-like bristles, in which the pollen, pressed 

 into clumps and pellets, is packed up to be carried home. Many of these Hymen- 

 optera moisten the pollen which they wish to collect with honey -juice, especially if 

 it is powdery or dust-like, so as to be able to knead it into the little baskets. For 

 instance, when the bees wish to obtain the pollen of the Plantain (Plantago) as 

 it emerges from the clefts of the anthers, they eject on it first of all some honey 

 from their extended sucking -tube, by which means the loose mass becomes 

 coherent and adapted for collection. It also frequently happens that the loose 

 pollen to be collected is already provided with juices from the perforated, turgid 

 tissue of the neighbouring petals. If the pollen is sticky provision of this kind 

 is not needed. The slightest disturbance and the most delicate touch are then suffi- 

 cient, and the pollen adheres to the body of the insect, even the smooth hairless 

 parts of the thorax, the abdomen, and the legs being covered with it. 



Since the sole use of insect-visits to flowers is the transference of the pollen 

 from one flower to another, it is evident that some restriction must be placed upon 

 its too extensive demolition. As a great part of the pollen can always be eaten in 

 the flower, or carried off to the nest as food for the larvae, it is necessary that some 

 should remain adhering to the body of the visitor, so that the stigmas of other 

 flowers may be adequately provided. This necessity is excellently met by the 



Fig. 243. — Honeyless Flower of Argemone Mexicana 

 with abundant pollen. 



