FRESH-WATER PRODUCTIONS. 38 



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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-fourths 

 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 ! Considering these facts, I think it would be an 

 inexplicable circumstance 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 Candolle's 

 remarks on the distribution of this plant, I thought that 

 the means of its dispersal must remain inexplicable ; but 

 Audubon states that he found the seeds of the great southern 

 water-lily (probably, according to Dr. Hooker, the Nelum- 

 bium luteum) in a heron's stomach. Now this bird must 

 often have flown with its stomach thus well stocked to 

 distant ponds, and then, getting a hearty meal of fish, 

 analogy makes me believe that it would have rejected the 

 seeds in the pellet in a fit state for germination. 



In considering these several means of distribution, it 

 should be remembered that when a pond or stream is first 

 formed, for instance, on a rising islet, it will be unoccupied ; 

 and a single seed or egg will have a good chance of succeed- 

 ing. Although there will always be a struggle for life 



