Te ewe ASD ULB OFNeeBelelL. lp IL N 19 
late spring or early summer. In the plants this condition probably occurs 
at a specific stage of seedling growth; in the insects the critical period 
appears to be when the young are most susceptible to heat, either by 
being unusually thin-skinned or by living in an exposed position. Many 
studies indicate that a large number of northern organisms are restricted 
by the 40° isotherm of early summer. This explains why some of the 
Dunesland plants and animals confined to this corner of Illinois may also 
be found much farther south in the Allegheny Mountains to the east and 
the Rocky Mountains to the west. The Dunesland is a peculiar little 
climatic relic as far as Illinois is concerned. 
Summarizing this history, the temperate deciduous forest in eastern 
North America is an isolated portion of a once tremendous forest stretching 
almost around the Northern Hemisphere. Our Dunesland area is a tiny 
relic of the life that colonized the tremendously disturbed conditions left 
by the last finger of the glaciers that extended into Illinois. In the Dunes 
are preserved some unusual communities of living things, including many 
species of plants and animals now found nowhere else in Illinois. These 
natural areas are a unique heritage of the past, and if they should disappear 
due to our own manipulations, they will never come back. It would be 
very easy for these vistas of prehistoric Illinois to be lost forever. In the 
economic expansion envisioned for Chicago and northeastern Illinois, these 
unique bits of nature could be swallowed up in picnic grounds, baseball 
fields, homesites, or factories. It is my own feeling that we would be remiss 
in our duty if we did not make every effort to preserve significant portions 
of the Dunes as wildlife study areas. 
Two objectives are involved in this preservation. One is the establish- 
ment of a wildlife area for scientific study. The difficulties of assessing 
biological problems in such an area are tremendous and the problems 
change as we accumulate more knowledge. For this reason the scientist 
needs an area which can be studied on a long-term basis. I also feel 
strongly that there must be hundreds of thousands of people who are 
interested in enjoying the Illinois natural landscape and would be thrilled 
by seeing some of its marvels. I have called these natural assemblages the 
heritage of Illinois, but they are a heritage that belongs to everyone. 
In order to preserve these unique communities for both scientific and 
recreational observation, I suggest action on many fronts. One front would 
be to help appropriate state, county, and city organizations, as well as the 
State Park System, in keeping wildlife areas of the parks and preserves 
inviolate except for the minimum disturbance needed to insure observation 
and understanding by the public. An uneducated public is an unseeing 
public. To make ours a seeing public, I would suggest that where the 
public does enter, well-marked trails be established, informative markers 
be put up at interesting spots, and brochures be prepared outlining the 
outstanding features of wildlife areas. If such brochures could be distributed 
at minimum cost to nearby schools, to organizations whose members are 
interested in natural history, and to the park visitors, I believe that we 
would stimulate a greater public appreciation of nature and open the eyes 
of many people to an interesting new world. 
