ADAPTATIONS IN ANIMALS AND PLANTS 47 



effectually engaged is by being held between two of the barbs, 

 which are merely spread apart, giving room for the grain, 

 as in Fig. 3. 



The fourth method observed of carrying these fertilizing 

 agents is an extraneous one, depending upon the glutinous 

 secretion from the stigma of plants that adheres to the feathers, 

 thus assisting the pollen to stick fast to the feather. Through 

 a high magnifying power is seen the thistle-like ending of the 

 vanes, the barbules frequently matted together by the sticky 

 secretion referred to, gathered from the flowers while the birds 

 are in search of food. Attached to the many pointed and 

 flattened surfaces are seen pollen grains of many kinds, 

 chiefly of very minute size, ready to depart or be taken on 

 anew at the next visit to a flower. In flowers in which the 

 wind is the agency for carrying the pollen, the grains are usually 

 small, light, and more or less dry and spherical, while in insect 

 flowers, the pollen of which is carried from one plant to another 

 by insects in search of honey, the parts are variously adapted 

 to cause the grains to adhere to the hairy underside of the 

 insect's body to promote their dispersion. In bird pollina- 

 tion the grains are carried in such diverse ways that this, 

 together with other data, combine to make it possible that 

 the humming-bird is the most wonderful distributer of pollen 

 known to the animal world. 



I am not content to leave the subject without noticing that, 

 as compared with insects, the local range of flight of humming- 

 birds is undoubtedly greater, and during the regular migra- 

 tions they make extensive flights, as I have already indicated. 

 Their summer home in eastern North America extends from 

 the Gulf of Mexico to half way across the British Provmces 

 and from the Atlantic Coast to beyond the Mississippi River. 

 In winter its range is southward, reaching into southern Florida, 

 into Veragua and the eastern portion of the Isthmus of Panama, 

 about eight degrees north of the equator. The equivalent of 

 some 2,000 statute miles is thus represented in the migrations 

 of this diminutive bird. The pollen taken en route during 

 migration, as the humming-bird takes its sip of nectar from 

 flower to flower, may gather in its repositories and be trans- 

 ported from place to place anywhere throughout its range. 



