22 SANDUSliY I^LORA. 



materially increased through the agency of man. 

 Several cultivated plants have run wild and become 

 well established there, including several species which 

 are seldom found flourishing in the wild state so far 

 north. The islands seem to have their full share of 

 weeds and most of these have probably been intro- 

 duced with impure seed. Others have probably been 

 transported in baled hay and in packing material, and 

 some, like the hore-hound, by sticking to people's 

 clothes. 



So numerous are the ways in which seeds may be 

 transported that it would seem quite possible for the 

 islands in the course of a few thousand years to have 

 acquired all the plants that grow on them without any 

 closer connection with the mainland than now" exists. 

 "When, however, we consider more carefully these means 

 of transportation in relation to all the species on the 

 islands, we find it difficult to understand how some of 

 them could have reached the islands in any of these 

 ways. 



A tornado passing first over the land and then the 

 islands might carry seeds of any sort, but it would 

 require more than one tornado to distribute seeds to 

 all the islands and if any of the islands owed part of 

 their plants to this agency we should expect to find on 

 them some species well distributed which do not grow 

 on the other islands at all, but this is not the case, 

 with the exception of some species recently introduced 

 by man. Other winds would not be likely to carry so 

 far any but the lightest of seeds. Violent winds coming 

 from the south where the mainland is nearest are gener- 

 ally accompanied by rain. 



Any plant whose seeds are safely transported in 

 the alimentary canal of birds might reach the islands in 

 this way. Of the species that grow in muddy or 

 marshy places and produce small seeds Hkely to be 

 transported in mud on the feet of woodcocks, etc., not 



