<!hap. xii. Means of Dispersal. 327 



has found and devoured a large supply of food, it is positively 

 asserted that all the grains do not pass into the gizzard for twelve 

 or even eighteen hours. A bird in this interval might easily be 

 blown to the distance of 500 miles, and hawks are known to look 

 out for tired birds, and the contents of their torn crops might thus 

 readily get scattered. Some hawks and owls bolt their prey whole, 

 and, after an interval of from twelve to twenty hours, disgorge 

 pellets, which, as I know from experiments made in the Zoological 

 Gardens, include seeds capable of germination. Some seeds of the 

 oat, wheat, millet, canary, hemp, clover, and beet germinated after 

 having been from twelve to twenty-one hours in the stomachs of 

 different birds of prey; and two seeds of beet grew; after haviDg 

 been thus retained for two days and fourteen hours. Fresh-water 

 fish, I find, eat seeds of many land and water plants: fish are 

 frequently devoured by birds, and thus the seeds might be trans- 

 ported from place to place. I forced many kinds of seeds into the 

 stomachs of dead fish, and then gave their bodies to fishing-eagles, 

 storks, and pelicans ; these birds, after an interval of many hours, 

 either rejected the seeds in pellets or passed them in their excre- 

 ment ; and several of these seeds retained the power of germination. 

 Certain seeds, however, were always killed by this process. 



Locusts are sometimes blown to great distances from the land ; I 



myself caught one 370 miles from the coast of Africa, and have 



heard of others caught at greater distances. The Kev. E. T. Lowe 



informed Sir C. Lyell that in November 1844 swarms of locusts 



visited the island of Madeira. They were in countless numbers, as 



thick as the flakes of snow in the heaviest snowstorm, and extended 



upwards as far as could be seen with a telescope. During two or 



three days they slowly careered round and round in an immense 



ellipse, at least five or six miles in diameter, and at night alighted 



on the taller trees, which were completely coated with them. They 



then disappeared over the sea, as suddenly as they had appeared, 



and have not since visited the island. Now, in parts of Natal it is 



believed by some farmers, though on insufficient evidence, that 



injurious seeds are introduced into their grass-land in the dung left 



by the great flights of locusts which often visit that country. In 



consequence of this belief 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. 



