CHAP. XII THE AZORES 259 



nine grains of earth on the leg of a woodcock a seed of the 



toad-rush was found which germinated ; while a wounded 



red-legged partridge had a ball of earth weighing six and 



a half ounces adhering to its leg, and from this earth Mr. 



Darwin raised no less than eighty-two separate plants of 



about five distinct species. Still more remarkable was the 



experiment with six and three-quarter ounces of mud from 



the edge of a little pond, which, carefully treated under 



glass, produced 537 distinct plants ! This is equal to a 



seed for every six grains of mud, and when we consider 



how many birds frequent the edges of ponds in search of 



food, or come there to drink, it is evident that great 



numbers of seeds may be dispersed by this means. 



Many seeds have hispid awns, hooks, or prickles which 



readily attach them to the feathers of birds, and a great 



number of aquatic birds nest inland on the ground ; and 



as these are pre-eminently wanderers, they must often aid 



in the dispersal of such plants.^ 



^ The following remarks, kindly communicated to me by Mr. H. N". 

 Moseley, naturalist to the Challenger, throw much light on the agency of 

 birds in the distribution of plants : — " Grisebach ( Veg. der Erdc, Vol. II. p. 

 496) lays much stress on the wide ranging of the albatross (Diomedea) 

 across the equator from Cape Horn to the Kurile Islands, and thinks that 

 the presence of the same plants in Arctic and Antarctic regions may be 

 accounted for, possibly, by this fact. I was much struck at Marion Island 

 of the Prince Edward group, by observing that the great albatross breeds 

 in the midst of a dense, low herbage, and constructs its nest of a mound 

 of turf and herbage. Some of the indigenous plants, e.g. Acjena, have 

 flower-heads '^hich stick like burrs to feathers, &c., and seem specially 

 adapted for transporation by birds. Besides the albatrosses, various 

 species of Procellaria and Puffinus, birds which range over immense dis- 

 tances may, I think, have played a great part in the distribution of plants, 

 and especially account, in some measure, for the otherwise difficult fact 

 (when occurring in the tropics), that widely distant islands have similar 

 mountain plants. The Procellaria and Puffinus in nesting, burrow in the 

 ground, as far as I have seen choosing often places where the vegetation 

 is the thickest. The birds in burrowing get their feathers covered with 

 vegetable mould, which must include sporesj and often seeds. In high 

 latitudes the birds often burrow near the sea-level, as at Tristan d'Acunha 

 or Kerguelen's Land, but in the tropics they choose the mountains for their 

 nesting-place (Finschand Hartlaub, Orn.der Viti-und Tonga- Inseln, 1867, 

 Einleitung, p. xviii. ). Thus, Puffiiius mcgasi nests at the top of the Koro- 

 basa basaga mountain, Viti Levu, fifty miles from the sea. A Procellaria 

 breeds in like manner in the high mountains of Jamaica, I believe at 7,000 

 feet. Peale describes the same habit of Procellaria rostrata at Tahiti, and 

 I saw the burrows myself amidst a dense growth of fern, &c., at 4,400 feet 

 elevation in that island. Phaethon has a similar habit. It nests at the 



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