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Illinois Natural History Slrvhv Bulletin 



Vol. 27. Art. 2 



The original staff of the station, in 

 18Q4, consisted of Frank Smith, who was 

 directly in charge and whose principal in- 

 terest was aquatic worms; Charles A. 

 Hart, entomologist and curator of col- 

 lections for the State Laboratory; Adolph 

 Hempel, who worked on protozoans and 

 rotifers; and Mrs. Dora Smith, who 

 served as microtechnician and was in 

 charge of the rooms in Havana. Miles 

 Newberry, who lived in Havana, had 

 charge of the cabin boat and acted as a 

 general field assistant. Others who were 

 present at some time during the first year 

 of operation were Ernest Forbes, for 6 

 weeks of general collecting. Professor 

 Thomas J. Burrill, a Mr. Clinton, a Mr. 

 Yeakel, and a Miss Ayers, all of the Uni- 

 versity of Illinois Botany Department, 

 who were collecting aquatic plants ; a 

 Professor Palmer, who was making chem- 

 ical analyses of the water ; Assistant Pro- 

 fessor Henry E. Summers of the Univer- 

 sity Physiology Department, who photo- 

 graphed the region ; and the staff artist. 

 Miss Lydia M. Hart. Professor Forbes 

 exercised general supervision over the sta- 

 tion work, planning and following its op- 

 eration. 



FISHES AND PLANKTON 



Within a year or so aquatic investiga- 

 tions were stepped up through increased 

 use of the laboratory and cabin boat at 

 Havana. At the beginning of this cen- 

 turv Frank Smith (1901:567) stated in 

 Science that the ichthyological survey of 

 Illinois had received much attention dur- 

 ing the previous 2 years and that a com- 

 prehensive report was soon to be pub- 

 lished. He also stated that Dr. C. A. 

 Kofoid had been studying the plankton 

 of the Illinois River for the previous 5 

 years. This short statement in Scietice 

 announced the progress being made on 

 two of the important contemporary- con- 

 tributions to aquatic biology, namely 

 Forbes Si Richardson's The Fishes of 

 Illinois (1Q08) and Kofoid's studies on 

 the plankton of the Illinois River. 



Shortly after, in an essay dealing with 

 "statistical ec()log\-," Forbes (1907^) pre- 

 sented a method for showing relation- 

 ships between individual species of fishes 

 and preferences of certain kinds of fishes 



with respect to features of the physical 

 environment. The validity of this method 

 depended upon the numbers of collections 

 that were available for study. Where 

 sufficiently large numbers of collections 

 could be mustered, Forbes compared ob- 

 served relationships with expected rela- 

 tionships and obtained a coefficient of as- 

 sociation by dividing the former by the 

 latter. A hypothetical example is given 

 below : 



Given species A and species B inhabit- 

 ing waters in the same general land area : 

 In 1,000 collections, species A occurred 

 159 times and species B 85 times. Thus, 

 the probability that they would occur to- 

 gether in anv single collection was 

 159/1,000 X 85/1,000 or 13,515 times 

 in a million or 13.5 times in 1,000, and 

 the probable number of these double oc- 

 currences in the 1,000 collections was 

 13.5/1,000 X 1,000/1 or 13.5 times. 

 However, in the 1,000 collections, spe- 

 cies A and species B were found together 

 in 40 ; thus, the coefficient of association 

 for species A and B was 40/13.5 or 2.96: 

 they were found together about three 

 times as often as was to be expected. 



This same type of reasoning was ap- 

 plied to show relationships between indi- 

 vidual species and the physical environ- 

 ment: stream, lake, pond, marsh; size of 

 water area and water movement ; bottom 

 of mud, sand, gravel, or rock. These co- 

 efficients of association are found fre- 

 quently in Forbes & Richardsons The 

 fishes of Illinois. Unfortunate!}" about 

 half the collections referred to in this pub- 

 lication were made without notes on wa- 

 ter current and bottom materials, so that 

 this method of showing association could 

 be applied only to stream, lake, pond, or 

 marsh, or to sectional distribution in the 

 state. Thus, when Forbes & Richardson 

 (1908:195) stated that the frequency 

 ratios for a fish were "3.19 for the smaller 

 rivers, 2.06 for creeks, and .58 for the 

 largest streams," they meant that these 

 hsh exceeded expectancy in "smaller riv- 

 ers" and "creeks" by about 3 and 2 times, 

 respectively, and were considerably below 

 expectancy in "the largest streams." A 

 coefficient of association of 1 indicated 

 correspondence with expectancy ; a co- 

 efficient below 1 indicated a negative re- 

 lationship. 



