408 FRESH- WA TER PROD U0TI0N8. 



immediately to acquire, as if in consequence, a wide 

 range. I think favorable means of dispersal explain 

 this fact. I have before mentioned that earth occa- 

 tionally adheres in some quantity to the feet and beaks 

 of birds. Wading birds, which frequent the muddy edges 

 of ponds, if suddenly flushed, would be the most likely to 

 have muddy feet. Birds of this order wander more than 

 those of any other; and they are occasionally found on the 

 most remote and barren islands of the open ocean; they 

 would not be likely to alight on the surface of the 

 sea, so that any dirt on their feet would not be 

 washed off; and when gaining the land, they would be sure 

 to fly to their natural fresh-water haunts. I do not believe 

 that botanists are aware how charged the mud of ponds is 

 with seeds; I have tried several little experiments, but will 

 here give only the most striking case: I took in February 

 three tablespoonfuls of mud from three different points, 

 beneath water, on the edge of a little pond; this mud when 

 dried weighed only six and three-fourth ounces; I kept it 

 'covered up in my study for six months, pulling up and 

 counting each plant as it grew; the plants were of many 

 kinds, and were altogether 537 in number; and yet the 

 viscid mud was all contained in a breakfast cup! Consider- 

 ing these facts, I think it would be an inexplicable cir- 

 cumstance if water-birds did not transport the seeds of 

 fresh-water plants to unstocked ponds and streams, situated 

 at very distant points. The same agency may have come 

 into play with the eggs of some of the smaller fresh-water 

 animals. 



Other and unknown agencies probably have also played 

 a part. I have stated that fresh-water fish eat some kinds 

 of seeds, though they reject many other kinds after having 

 swallowed them; even small fish swallow seeds of moderate 

 size, as of the yellow water-lily and Potamogeton. Herons 

 and other birds, century after century, have gone on daily 

 devouring fish; they then take flight and go to other 

 waters, or are blown across the sea; and we have seen that 

 seeds retain their power of germination, when rejected 

 many hours afterward in pellets or in the excrement. 

 When I saw the great size of the seeds of that fine water- 

 lily, the Nelumbium, and remembered Alph. de CandoUe's 

 remarks on the distribution of this plant, I thought that 



