POLLEN. 



332 



POLLEN. 



ing has a strong tendency to weaken off- 

 spring. The same principle liohls true to 

 a certain extent among plants. " A study 

 of the devices provided by nature to in- 

 sure cross-fertilization," says Dr. Fletcher, 

 " forms one of the most charming branches 

 of the whole study of botany." The great 

 naturalist Charles Darwin is recorded as 





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—After Fletrhn: 



sajing that the general jirinciplecan be seen 

 running through all branches of the animal 

 and the vegetable kingdom. Although some 

 plants, he says, can be and are fertilized by 

 their own pollen, it is always of greater ben- 

 etit to their descendants if the flowers be fer- 

 tilized by pollen from other flowers of the 

 same kind growing upon other plants. Dar- 

 win summed up his observations with the 

 statement that " Nature abhors perpetual 

 self-fertilization. " Since then, says Dr. 

 Fletcher, " endless Cibservations have con- 

 firmed the accuracy of Darwin's law, and it 

 has been found that in the vast majority of 

 plants special appliances exist which will 

 secure a more or less frequent inter-cross." 

 And then he goes on to say that these ajv 

 pliances completely exclude the possibility 

 of self-fecundation. 



Coming nowto the special agencies for the 

 fertilization of plants, we may say in a gen- 

 eral way that there are two, the animate and 

 the inanimate. Among the first mentioned 

 may be included wind, rain, and the force of 

 gravity. The. v can be no question but that 



pollen from some plants is blown not only 

 from rtower to flower, but, in son e cases, 

 clear out to sea. Cases are on record where 

 pollen from certain species of pines has 

 been found hundreds and hundreds of miles 

 floating in the air and lodging in the rig- 

 ging of ships. Rain doubtless has a hirge 

 influence, because it spatters the fertilizing 

 element from one flower to another. Grav- 

 ity must necessarily convey the pollen lo- 

 cated on the tops of the trees or plants to the 

 blossoms situated further down, whether on 

 the same or other plant of the same species. 

 Among the animate agencies for the dis- 

 tribution of pollen, insects (and especially 

 bees) are by far the most important. To a 

 very limited extent animals and birds may 

 assist. While insects other than bees un- 

 doubtedly perform a very valuable service, 

 the honey-bee, from the very fact that it is 

 out earlier in the spring than all other in- 

 sects, must necessarily be regarded as by far 





— Afici Fietchei . 



the most imp rtant means of bringing about 

 cross-pollination among our fruit-trees; and 

 even when other insects are in the air, it out- 

 numbers any other species, and possibly, in 

 some cases, all other species combined, a 

 thousand to one. Its general sha]ie and size, 

 the special construction of its tongue and its 

 legs, all together make it especially adapt- 

 able for receiving and carrying pollen. 



