38 THE MEANING OF EVOLUTION 
pod, a total of more than six hundred and thirty thou- 
sand seeds. If each of these could find lodgment on 
a plot eighteen inches square, produce a similar num- 
ber of seeds and plant them all, the result would be 
overwhelming. The fourth generation would cover 
land and sea, from pole to pole, one hundred layers 
deep. But there is no such danger. Year by year 
the mulleins hold their own and no more. Any par- 
ticular field may have more or less, but in the long 
run the average for a district is about the same. Some 
of the seeds are poor and thin. These scarcely sprout. 
Others spring up into thin-skinned plants, and the 
first frost nips them. Still others lack the woolly 
coating in its finest abundance, and the browsing ani- 
mals eat these. Others lack power to put out a wide- 
_ ranging root supply and the first drought kills these. 
Still others fail to send up a vigorous stem and the 
passing animal knocks them over and they die. Of 
the few that are still surviving, some produce such 
small and inconspicuous blossoms that the insects 
scarcely see them, and they go unfertilized. In the 
end only the aristocrats of the group are left, aristo- 
crats in the best sense of the word. These are strong, 
thrifty, and beautiful, and are provided with every 
defense known to the mullein world. From these the 
mulleins of the next generation will spring. Again 
Nature will select the best of these, by a repetition 
