Seed-Carriers 229 



more than one plant has been introduced not only from 

 one continent but from one hemisphere to another within 

 recent times. 



The ''Bathurst bur," among others, is a striking ex- 

 ample of the successful emigrant. Growing in Patagonia, 

 it got itself conveyed to Australia, where it has flourished 

 ever since in the most rampant manner. The first step 

 was to hook its burs into the tails and manes of horses, 

 which it did most effectually; and then, as chance would 

 have it, some of these same horses were imported into 

 Australia, burs and all, for so thoroughly were they 

 entangled that the animals had not been able to shake 

 or rub them all off, even during the voyage. Some no 

 doubt were got rid of, but enough remained to make a 

 fresh start in the new country; and they did it with such 

 energy that within a few years it was found necessary to 

 pass an act of Parliament ** against the growth of thistles," 

 and all persons allowing them to remain on their land, or 

 even on their half of the road, were made liable to heavy 

 fines. 



But birds are the great carriers; and the migrants, espe- 

 cially, transport such seeds as lay hold of them to much 

 greater distances than quadrupeds , ever travel, at least 

 without the help of man. 



There is a species of sedge which grows by the water 

 in the highlands of Jamaica, whose fruit is provided with 

 long bristles, something like a shepherd's crook, the 

 hooked part being so closely fitting and elastic as to grasp 

 the finest hairs, if drawn across the back of the hand. It 

 grasps them so tight, moreover, as to pull them out 

 sooner than let go. The highlands where this sedge 

 abounds are the spots generally first touched by migratory 



