SEVENTH ANNUAL MEETING 15 



Doctor Cowles's personal work during the past year has lain 

 outside the state, together with a large part of the work of his 

 students. One of the latter, Mr. Ullrich, has maintained dur- 

 ing the summer season a large number of atmometer stations 

 for an extensive study of the moisture conditions of a ravine 

 rear Glencoe, 111. Exact evaporation data were obtained for 

 different situations in various parts of the ravine; and the soil 

 moisture was determined weekly in a way to give the range of 

 conditions throughout the season. The wilting co-efficient of 

 the soils having been determined, the approximate amount of 

 moisture available for plant growth was shown. 



Mr. Hankinson is preparing for publication his data of the 

 survey of the prairie and forest near Charleston, made in 

 August, 1910, in co-operation with Adams and Transeau. 



Doctor Transeau has continued his work on the periodicity 

 of the occurrence and reproduction of the Algae. During the 

 year past an attempt has been made to analyze the environ- 

 mental factors related to these changes in the Algae. In 

 addition to temperature records, the variations in the osmotic 

 pressure of natural waters have been studied by means of the 

 freezing-point method. These data have shown that, contrary 

 to the accepted notion, when ponds and pools dry up in the 

 summer, the concentration of the solution is not increased, 

 but is usually greatly diminished. The highest concentrations 

 occur during the periods of high water in spring, and during 

 the early rainy period of autumn. 



The evaporation rates and the soil moisture conditions in 

 several of the forest-plant associations of the Chicago area, 

 and in some bits of undisturbed prairie have been studied in a 

 quantitative manner by Dr. Geo. D. Fuller and some of his 

 students during the past four years. An attempt has been 

 made, with considerable success, to relate these determinations 

 to the succession of plant associations. These studies include 

 areas at Miller, and Otis, Ind., Palos Park, and Chicago Lawn, 

 111. A paper by Mr. J. F. Graves upon the present program 

 gives some of the results of his studies in evaporation and 

 soil moisture conditions in cultivated and natural areas. The 

 data obtained during the years 1910-1913 have been collected 

 by Dr. Fuller, and are now in manuscript and will be published 

 at an early date. 



We have finally to report action taken yesterday by your 

 committee, looking to a program of correspondence and in- 

 quiry, and a search for relic situations characteristic of the 

 more important ecological features of primitive Illinois. Such 



