SEEDS TRANSPORTED BY WIND. 
43 
chances for distribution, especially for long distances. 
The minute size of spores of most of the fungi are 
given as reasons why so many of them are so widely 
distributed. 
Why is a boy or man of light weight chosen to ride the 
horse on the race track ? That the animal may have less 
weight to carry and thereby use his surplus strength in 
making better time. The less weight the parachute of 
the seed of the willow-herb has to carry, the greater the 
chances for success in making a long journey. Of the 
willow-herb it takes one hundred seeds to weigh a milli- 
gram, including the hairs attached to them, and it would 
take thirty thousand to weigh as much as an ordinary 
white bean. 
25. Seeds with parachutes. — Many years ago large por- 
tions of Huron and Sanilac counties of eastern Michigan 
were swept by a fire so severe that the timber was all 
killed. Fifteen years later the woody growth consisted 
mostly of willows, poplars, and birches. The seeds of all 
kinds of willows and poplars are very light, and are pro- 
duced in immense quantities. Like those of the great 
willow-herb, they are beautifully constructed for making 
long journeys through the air — a fact that explains the 
frequency of these trees in burned districts. A consider- 
able number of seeds and fruits grow with a parachute 
attached at one end, not to prevent injury by falling 
from the tree top, but to enable the wind to sustain and 
transport them for a longer distance. 
