AUTUMN WINDS AND WINTER FLOODS 279 



the flood. On one low flat near the river I found 

 great patches of refuse, broken twigs, cases of caddis 

 worms, here and there a chrysalis or a cocoon, and 

 abundance of seeds. Among many unknown fruits 

 and seeds I could see a great many Alder-nuts, which 

 happen to be familiar to me. 



Alder grows by preference on the banks of streams, 

 and during the gales of autumn and winter the ripe 

 nuts are shaken out of the cones. Many of them 

 must fall from the overhanging boughs into the water, 

 and be swept down the stream. Do they sink or 

 swim in water? It was a simple thing to try. I 

 threw a number of the nuts into a beaker of water, 

 and found that they all floated. They went on floating 

 all through the winter, and many of them germinated 

 on the surface in spring or earlier. Do all seeds swim 

 in water ? I went to a seedsman and bought a dozen 

 packets of flower-seeds, taking the first which came to 

 hand without selection. All sank in water except a small 

 proportion of each sort (probably dead seeds) which 

 contained air and floated. Among the rest were the 

 so-called seeds of two Composites, which floated. 

 But these were not mere seeds. They were fruits 

 invested by the withered husks, which enclosed plenty 

 of air. 



On cutting open an Alder-nut the wall was found 

 to be excavated by numerous small cavities. I wished 

 to ascertain whether these were air-tight compartments 

 or not. I therefore exhausted the air from a receiver 

 which contained some entire and some broken Alder- 

 nuts floating on water. None of them sank, though 

 the air was kept exhausted for a long time. I 



