378 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1958 
complicated by the fact that living organisms are themselves a part of 
the environment of other living things. 
Now environment, any way we consider it, is a mighty complex sys- 
tem in itself. But there is an old rule and a good one that the way to 
tackle a complicated problem (in science, business, or personal rela- 
tions) is to take it a bit at a time, provided one doesn’t ever lose sight 
of the whole. Perhaps as useful a breakdown as any is the following: 
Earth : Lithosphere, studied by geologists, geographers, soil scientists. 
Air: Atmosphere, studied by climatologists, meteorologists, ete. 
Water: Hydrosphere, studied by oceanographers, limnologists, hydrologists, etc. 
Life: Biosphere, studied by biologists. 
To these might be added A/ind—the Psychosphere, studied by psy- 
chologists, anthropologists, and other social scientists. 
Clearly no ecologist can become all these various specialists rolled 
into one. But he must be enough at home in their various fields to 
draw upon them as he needs, and even to contribute what he can. In 
particular he must learn to work the borderlines between them and 
in some degree become what has been called a “specialist in the gen- 
eral.” To do this at the sacrifice of thoroughness or the ability to do 
scrupulously accurate, detailed work when necessary, would, however, 
be as fatal to him as to any other scientist. 
By way of examples of some of the things that are of especial! con- 
cern to him from each of these several aspects of environment let us 
take: 
Earth (the solid lithosphere).—Here he is interested in the obvious 
irregularity of surface forms and chemistry, both so significant for life. 
Mountains and valleys, ores and nutrient minerals are where we find 
them, not predictable on any simple geometrical plan. This means 
that the ecologist cannot, to the same extent as the chemist, safely rely 
upon universal formulas. Each situation must be studied on its 
merits. The rainfall which suffices to produce forest in a cool region 
may mark desert nearer the Equator. The failure of one plant to form 
seed in a given locality may be due to temperature or mineral defi- 
ciency ; in another to the absence of a particular insect. 
Yet behind all the diversity and irregularity there exist certain 
trends toward order and equilibrium. Rivers tend to seek base level, 
extreme differences in elevation and mineral content to be reduced, 
soils to develop toward maximum fertility, and so on. Frequently 
though such trends may be interrupted or reversed, they are not to be 
ignored. 
Air (the gaseous atmosphere).—Gas, or spiritus in classical lan- 
guage, long the most mysterious and elusive of the states of matter 
proved in the end to be most amenable to experiment and the simplest 
for mathematical treatment. It was the study of gases that unlocked 
the gate to modern chemistry and physiology. The gaseous envelope 
