1906] GANONG—NASCENT FOREST OF MISCOU BEACH QI 
from such a diversity of natural habitats, and yet live in this peculiar 
situation upon an equal footing, shows how far we are from under- 
standing the real bases of physiological adaptation, and further 
shows that in the study of the physiological life-histories of plants 
lies the most important and attractive field for the ecologist of the 
near future. 
So much for the expcsed parts of the dune beaches. But in 
addition they offer, upon their inner or leeward slopes and in the 
hollows, situations more sheltered, not so much from the sun, since 
Fic. 6.—Typical hollow between outer dune beaches; the tall grass is all beach 
grass, but the small plants among it are the common strawberry. 
their average course is nearly north and south, but from the westerly 
winds. The older inner dune beaches also are protected to some 
extent by the newer outer ones, as well as by their slightly lower 
average level. The difference between leeward slope and hollow is not 
simply one of degree of shelter, however, but also of physical condi- 
tions, for the hollow is much nearer the source of water supply, 
the free table of which is not over a foot or two beneath the surface. 
In consequence of these differences we can recognize three distinct 
phases of vegetation: first, a larger development on the leeward 
