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oeciisional. and as the direction of winds is tiiouwht to be so variable, it has be- 

 come customary to speak of them as among the •'occasional" or "accidental" 

 factors in plant migrations. 



Darwin objected to tlie term ''accidental," and for the l)est of reasons, suggest- 

 ing as a substitute tlie word "occasional." But to the writer it seems that the 

 second term, while not quite as unscientific as the former, is in other respects no 

 imjjrovement. For even if the influence of winds in seed diffusion were limited 

 to tlie lighter or appendaged seeds, it would still be objectionable, as must be 

 obvious. 



By no means, however, are we justified in holding that winds affect only 

 lighter seeds, and that moderate winds have little or no influence on heavier fruits 

 and seeds, which any one may readily demonstrate for himself by observation. 

 The writer shared in the prevailing opinion until observations convinced him of 

 the contrary, and showed that ordinary winds have sufficient force to transport 

 even the heavier fruits and seeds, when borne on parts some distance above the 

 ground, to considerable distances. In considering the value of winds as plant 

 diffusing agents, several incidentals occur more or less influencing their effective- 

 ness, which it may be well to mention. 



As is obvious, height of the plant is an important factor. Were a fruit as 

 large as the cocoa-nut to be borne on a low plant close to the ground, winds could 

 have no appreciable effect on its fall; but growing as it does, on a tall tree, the 

 strong winds, such as are common in the regions it inhabits, may drive the fruit 

 in falling considerably from the perpendicular before it has reached the ground. 

 Again, tall jilan*.s are likely to travel more directly with winds in regions where 

 these blow mainly from one direction during the fruiting season, owing to the fact 

 that the direction of the wind is less affected by irregularities of land surface at 

 some distance above the ground. 



Rigidity of trunks and branches is an item worth considering. Flexible stems 

 and branches will lean with the wind, and drop their fruit farther on the side 

 from the wind than in the case of more rigid ones. 



Weight, bulk and form of fruits have their values. Lighter unappendaged 

 fruits and seeds may be carried a considerable distance by winds, even when pro- 

 duced upon low growing plants. Where the l)ulk of surrounding parts is large 

 in |)roportion to the size of the seeds, it not only makes the force of wind more 

 elective, but in some instances it is probable these bulky parts by their decay en- 

 rich the spot upon which the fruit finally rests, and thus helps in giving the young 

 seedlings a start in life, and in traveling across infertile belts. 



