picture of how healthy land maintains itself as an organism. 
We have two available norms. One is found where land physiology remains 
largely normal despite centuries of human occupation. I know of only one
such 
place: northeastern Europe. It is not likely that we shall fail to study
it. 
The other and most perfect norm is wilderness. Paleontology offers abundant

evidence that wilderness maintained itself for immensely long periods; that
its 
component species were rarely lost, neither did they get out of hand; that

weather and water built soil as fast or faster than it was carried away.
Wilder- 
ness, then, assumes unexpected importance as a laboratory for the study of
land- 
health. 
One cannot study the physiology of Montana in the Amazon; each biotic 
province needs its own wilderness for comparative studies of used and unused

land. It is of course too late to salvage more than a lop-sided system of
wilder- 
ness study areas, and most of these remnants are far too small to retain
their 
normality in all respects. Even the National Parks, which ran up to a million

acres each in size, have not been large enough to retain their natural predators,

or to exclude animal diseases carried by livestock. Thus the Yellowstone
has 
lost its wolves and cougars with the result that elk are rining the flora,

particularly on the winter range. At the same time the grizzly bear and the

mountain sheep are shrinking, the latter by reason of disease. 
While even the largest wilderness areas become partially deranged, it required

only a few wild acres for J. 3. Weaver to discover why the prairie flora
is more 
drouth-resistant than the agronomic flora which has supplaqnted it. Weaver
found 
that the prairie species practice "team work" underground by distributing
their 
root-systems to cover all levels, whereas the species comprising the agronomic

rotation overdraw one level and neglect another, thus building up cumulative

deficits. An important agronomic principle emerged from Weaver's researches.