282 ROUND THE YEAR 



it, perhaps for many days together, in the same place. 

 In the lower reaches of the river the drift comes under 

 the influence of the tides, which carry it to and fro 

 for a long time. During this protracted flotation, 

 seeds, seed-vessels, and even broken-off fragments 

 of living plants may retain their power of ger- 

 mination or renewed growth. Some, like the nuts 

 of the Alder, float a long time and germinate in 

 spring at the surface of the water. The seedlings of 

 such plants would readily establish themselves when- 

 ever they happened to be stranded in a suitable 

 place. The seeds and seed-vessels, which float for 

 months in the river-drift, nearly always float equally 

 well in sea-water, and afterwards germinate, as Dr. 

 Guppy ascertained by actual experiment. Ice sends 

 great numbers to the bottom after the thaw, but many 

 are not injured even by repeated freezing. Some 

 seedlings even gain fresh vigour in the ice, and will 

 put forth their leaves during the daily thaw, though 

 every night they are frozen up again. 



The floating drift by no means includes the seeds 

 of all the common water-plants of the river. It would 

 be nearer the truth to say that it includes none of 

 them. Water-lilies, the Water Persicaria (Polygonum 

 amphibium)) the W T ater Ranunculus, the Water forget- 

 me-not and other plants which live actually in the 

 water are unrepresented in the drift. Their seeds 

 have little or no floating-power. These plants prob- 

 ably owe their dispersal to birds. Charles Darwin 

 tells us that hard seeds pass uninjured through .even 

 the digestive organs of a Turkey. He picked up in 

 his garden twelve kinds of seeds from the droppings 



