MINUTES OF NINTH ANNUAL MEETING 15 



couraging statement that there are still thousands of acres of 

 native prairie remaining - in the state, about two thousand, in- 

 deed, within the city limits of Chicago, so little disturbed by 

 man that they are available for ecological studies. He is 

 studying the composition and succession of the plant associa- 

 tions characteristic of the different kinds of prairie in this 

 state, and the data obtained have led him to the following gen- 

 eral tentative conclusions: 



1. Starting with the various pioneer habitats of the prairie 

 regions of Illinois, as the physiography of these habitats de- 

 velops, there follows a dynamic succession of associations of 

 prairie plants ; the associations differing in each particular case 

 according to the initial habitat but ultimately all merging into 

 a temporary climax type of prairie. 



2. Andropogon furcatus in general is the most abundant 

 grass on this temporary climax prairie ; a fact suggesting that 

 it may be the mesophytic climax grass of this region. 



3. The above data support the theory that the black-soil 

 prairies of Illinois originated in glacial lakes and swamps and 

 have existed as prairie since glacial times. 



4. In a large general way the trend of the associations on 

 the black-soil and clay prairies follows the change in moisture 

 content of the soil as the physiography of the region develops. 



Additional studies in this field have been made by Dr. A. G. 

 Vestal, who has worked out the status of the prairie relics in 

 the sand dunes of Lake Michigan with special attention to 

 lines of contact between the prairie and black-oak formations ; 

 and by Mr. Hankinson, who has continued his studies on the 

 animal life of the prairie remnants of Coles county and neigh- 

 boring districts. 



Further studies of our aquatic biology have been made by 

 the State Laboratory of Natural History, which has brought to 

 a practical conclusion its long course of work on the Illinois 

 River and the lakes of its bottom lands. The principal work 

 of the last season has been the making of over five hundred 

 collections from the bottom, by means of dredges, mud dip- 

 pers, and the like, in various localities from Peoria to the 

 mouth of the stream, intended mainly to verify conclusions 

 drawn from the studies of previous years. 



