4 
The field work of the first two years was comprehensive of all 
aquatic forms and situations, including plankton collections, quan¬ 
titative as well as qualitative, shore and marginal collections of 
mollusks, insects, and crustaceans, dredgings from the bottom at 
various depths, and collections of fishes and other vertebrates, by 
means of various kinds of apparatus. The next three years were 
mainly devoted to plankton work in the Havana district, and the 
last four, spent mainly at Meredosia, Ottawa, and Henry, to work 
on the fishes of the Illinois system. During our period of active 
operation, approximately six thousand collections were made in all, 
of which five hundred were fishes and two thousand were plankton 
collections, the remaining thirty-five hundred consisting of insects, 
mollusks, and a general variety of aquatic and subaquatic forms. Six 
hundred and forty of the plankton collections were made at Ha¬ 
vana by strict quantitative methods, and were thus available for a 
comparative study of the product of various waters at all times of 
the year. Two hundred and thirty-five of these were from the main 
stream and four hundred and five from other stations adjacent. 
Besides our purely biological work, weekly samples of waters 
were regularly examined by chemical methods for three and a half 
years, under an arrangement with the Water Survey of the state, 
established in 1895. 
I can not attempt, in this rapid outline, to present even in brief¬ 
est summary the results of this work, but may be permitted to ab¬ 
stract a few general statements from its two most important publi¬ 
cations—the report on the fishes of the state and that on the plank¬ 
ton collections, the former prepared by Mr. Richardson and myself, 
and the latter by Dr. Kofoid. 
From our fish collections it appears that the Illinois basin is thor¬ 
oughly representative of the state at large. Of the hundred and fifty 
species of Illinois fishes known to us, a hundred and twenty-eight oc¬ 
cur in the Illinois or its tributaries. Of the twenty-three species not 
found by us in that basin, eight are excluded by their definitely south¬ 
ern range, six by their distinctly northern distribution, and four are 
as definitely western, while the five remaining are so rare in Illinois 
that they appear in any of our waters only by an unusual chance. 
About three dozen of the hundred and twenty-eight species in the 
Illinois basin have a marketable value as food. A dozen of the 
best species are of really good quality, and half of these are among 
the best freshwater fishes in the country. 
From our plankton studies it appeared that the average ratio 
of plankton organisms to the water of the main stream, year in 
