■ WATER TRANSPORTATION OF PLANTS. 19 
in another sense, by catching and killing large numbers of 
minute animals, on which the plant lives in part. The tips 
of the stems at all times of the year are rather compact, 
made up of young leaves and stems, and in the middle 
of the summer, as well as at other times, many may be 
seen severed from the parent plant, floating in the water, 
ready to accept the assistance of any favorable current or 
breeze and start out for homes of their own to found new 
colonies. These olive-green tips, or buds, vary much in 
size, but the largest are the size of the end of one’s 
little finger. Late in autumn or early winter, when cold 
threatens, the tender buds contract a little, and, having 
thus become heavier than water, slowly go to the bottom 
to spend the winter safely protected in the soft mud. 
All the plant perishes except these buds. With the 
lengthening days of spring the melting ice disappears, 
and genial sunshine gives notice to the dormant buds 
that it is safe to come out again. The buds begin to 
expand, become lighter than water, and are soon seen 
spreading out at the surface and producing branches and 
leaves. Ducks and other water-fowl not infrequently 
carry some of these wet buds sticking to their feathers 
or legs. 
In this connection the following plants may be examined 
from time to time : Lenina, Wolffia, Anacliaris ( Elodea ), 
Myriophyllum, Cabomba, and several species of Potamo- 
geton. I have seen the leaves of lake cress, Nasturtium 
lacustre, often spontaneously separate from the stem, 
