2^4 Seed-Scattering 



almost absolutely motionless, so extremely light are 

 they, being, in fact, rather like pollen than seeds. 



Spores, owing to this extreme lightness, travel 

 immense distances over sea and land, and are to be 

 found in almost all dust, whether of town or country ; 

 but in damp weather they are not carried so far, and 

 some of the mosses keep the capsules in which their 

 spores are contained tightly closed, except when the 

 air is dry enough to ensure them a long journey. 



Seeds, even the smallest, with very few exceptions, 

 fall straight to the ground when the air is still. Even 

 the tiny seeds of the poppy, campanula, and others do 

 this ; but then, on the other hand, small as their 

 weight is, they require something of a shake to dis- 

 lodge them at all, and as they get this only when there 

 is a tolerably strong puff of wind, they must needs be 

 carried some little distance. 



It might seem that large, heavy seeds would be at a 

 disadvantage in respect of wind transport ; but as 

 they need a stronger shake to detach them, they do 

 not begin their journey till the wind is blowing with 

 some little force ; and then again, being generally 

 borne by trees, and tall trees too, they start at a 

 favourable height, and are often carried a long way. 



Seeds have, indeed, been raised as much as 5,400 

 feet in the air by the wind ; but hurricanes are usually 

 local, and do not convey what they snatch up more 

 than a few miles at the utmost. 



But we have been looking upon seeds hitherto as if 

 they were themselves perfectly helpless and inactive, 

 which is very far indeed from being the fact. Many 

 of them have special means of their own for ensuring 

 or helping their conveyance from place to place — 



