MEANS OF DISPERSAL 409 



appeared, and have not since visited the island. Now, in 

 parts of Natal it is believed by some farmers, though on in- 

 sufficient evidence, that injurious seeds are introduced into 

 their grassland in the dung left by the great flights of locusts 

 v^'hich often visit that country. In consequence of this be- 

 lief Mr. Weale sent me in a letter a small packet of the dried 

 pellets, out of which I extracted under the microscope several 

 seeds, and raised from them seven grass plants, belonging to 

 two species, of two genera. Hence a swarm of locusts, such 

 as that which visited Madeira, might readily be the means of 

 introducing several kinds of plants into an island lying far 

 from the mainland. 



Although the beaks and feet of birds are generally clean, 

 earth sometimes adheres to them : in one case I removed 

 sixty-one grains, and in another case twenty-two grains of 

 dry argillaceous earth from the foot of a partridge, and in 

 the earth there was a pebble as large as the seed of a vetch. 

 Here is a better case : the leg of a woodcock was sent to me 

 by a friend, with a little cake of dry eartli attached to the 

 shank, weighing only nine grains ; and this contained a seed 

 of the toad-rush (Juncus bufonius) which germinated and 

 flowered. Mr. Swaysland, of Brighton, who during the last 

 forty years has paid close attention to our migratory birds, 

 informs me that he has often shot wagtails (Motacillae), 

 wheatears, and whincats (Saxicolse), on their first arrival 

 on our shores, before they had alighted ; and he has several 

 times noticed little cakes of earth attached to their feet. 

 Many facts could be given showing how generally soil is 

 charged with seeds. For instance. Prof. Newton sent nie 

 the leg of a red-legged partridge (Caccabis rufa) which had 

 been wounded and could not fly, with a ball of hard earth 

 adhering to it, and weighing six and a half ounces. The 

 earth had been kept for three years, but when broken, 

 watered and placed under a bell-glass, no less than 82 plants 

 sprung from it: these consisted of 12 monocotyledons, includ- 

 ing the common oat, and at least one kind of grass, and of 70 

 dicotyledons, which consisted, judging from the young leaves, 

 of at least three distinct species. With such facts before us, 

 can we doubt that the many birds which are annually blown 

 by gales across great spaces of ocean, and which annually 



