SEEDS TRANSPORTED BY WIND. 
39 
conditions are almost perfect. Over the snow the wind 
drives the bracts, which drag along the branch of fruit 
much as a sail propels a boat. The curving of the edges 
of the bract toward the fruit enables the wind to catch it 
all the better, and to lift it more or less from the snow. 
With changes in the direction of the wind, there is an 
opportunity for the fruit of a single tree, if not too much 
crowded by others, to spread in all directions. After 
watching these maneuvers, no one could doubt the object 
of the bent bracts of the basswood, and as these vary 
much in length and width and shape on different trees, it 
would seem that perhaps nature is still experimenting 
with a view to finding the most perfect structure for the 
purpose. 
About one hundred and thirty paces west of the house in 
which I live stand two birch trees. One windy winter 
day I made some fresh tracks in the snow near my house, 
and within a few minutes the cavities looked as though 
some one had sprinkled wheat bran in them, on account 
of the many birch seeds there accumulated. 
Other fruits in winter can be experimented with, such 
as that of box elder, black ash, birches, tulip tree, button- 
wood, ironwood, blue beech, and occasionally a maple. 
22. Buttonwood balls. — Nature seems to have no end 
of devices for sowing seeds to advantage. Here is one 
which always interests me. The fruit of the buttonwood, 
or sycamore, which grows along streams, is in the form 
of balls an inch and a half in diameter. These balls 
