CULTURE AND THE BIOLOGICAL HABITAT 133

earlier, totally unrelated to the biological habitat and quite inimical to
effective control of it. One side of a river, swamp, field, or lake may
fall within the jurisdiction of one nation, state, or county, the other
side within the jurisdiction of a different political unit. Unless all the
various political units within a given ecological region join in aggressive
action against mosquitoes, flies, rats, or other disease carriers, the efforts
of any one of them are futile. Here in the United States, for example,
mosquito-abatement work has often been impossible because one of a
number of counties—the usual units of such work—has refused to co-
operate. Even more serious has been the failure of a number of munici-
palities strung along a river to cooperate in preserving the purity of the
water that they jointly utilize. It is still common practice for each such
city, in accordance with its traditional political rights, to draw its do-
mestic water from upstream and dump its sewage downstream, with the
result that only the city situated nearest the headwaters secures reason-
ably pure water for domestic use. Our county and city jurisdictions are
slowly being subordinated to state and Federal control of public health
matters. In Europe, however, joint large-scale attack on problems of
public health is made almost impossible by the fact that national bound-
aries bisect ecological regions; and nations are much more inclined to
make war upon one another than to unite in a struggle against micro-
organisms.

The irrelevance of traditional political jurisdictions to problems of
public health is growing more rather than less significant. As the diseases
and the plant and animal pests of the various regions of the world are
becoming more and more universalized, unprecedented problems of bio-
logical control are arising. Thus many of the diseases that were a short
while ago limited to tropical regions, and that were then considered to
be diseases of tropical climates, are spreading into temperate regions; and
the traditional diseases of the temperate zones are demonstrating an equal
ability to thrive in the tropics. To check the continual spread of pests,
bacteria, and viruses each nation or other political unit can of itself do
little. Control of the biological habitat is becoming more and more a
world rather than a local problem. Ultimately, therefore, the ability of
man to maintain his dominant position in the biological world rests upon
his ability to organize himself on world-wide levels.

War and the Biological Habitat.—Whenever the inhabitants of a region
are distracted by other concerns from the struggle to maintain a social
balance within the biological habitat, that habitat immediately begins to
return to nature. As the householder distraught by marital discord may
let his lawn and flower beds run wild, so the society disrupted by internal
dissensions or preoccupied with warfare may neglect its fields and herds
and let nature have its way with them. In the past the failure of a society