grounds and their food supply, and that of these the latter is the 
most important. We especially need to know, therefore, what the 
more valuable fishes feed upon as fry, as young, and when full grown, 
under various conditions, and at different times of the year; where 
their food supply is most abundant; whether their most important 
food resources are at all times sufficiently accessible to them, and 
under sufficiently favorable conditions; what their food species feed 
upon in turn; and so on down through the series of forms de¬ 
pendent one upon another until we reach the primary sources of their 
food, and the conditions of its greatest abundance and availability. 
Next we need to know, for each important fish, its spawning times 
and places; where such places are to be found; whether the fry can 
escape from them in clue season, and if not, why not, and what can 
be done about it; whether such most desirable spawning grounds 
are present in the necessary abundance and of convenient access, and 
if not, what can be done about that. All this involves, as it seems 
to me, a systematic survey and description, from the fisheries stand¬ 
point, of the whole congeries of waters—main river, tributary streams, 
and connected lakes—so made as to lead to a clear discrimination 
of their individual features as homes for fishes or places of oc¬ 
casional resort, and leading also to a classification of them in definite 
groups and kinds, each kind containing similar waters with simi¬ 
lar surroundings. As soon, however, as we attempt to analyze, in 
this sense, the environment and the needs of the more important 
fishes, we find the essential elements of their welfare so interwoven, 
in one direction or another, with those of virtually all the other or¬ 
ganisms in their neighborhood, and determined at so many points 
and in so many ways by the whole local system of things—biolog¬ 
ical, chemical, and physical, aquatic and terrestrial, climatic and sea¬ 
sonal—that there is evidently no fit way to our end except by a 
general survey and analysis of that system as a whole. 
My proposed program of investigation begins, consequently, with 
a general natural history survey of the river and its tributary waters, 
—with fishes, of course, in the lead, where they belong- biologically 
as well as economically, since in them all the life of the waters cul¬ 
minates and centers. A great river system however, is a large and 
complicated unit to handle as one, and the Illinois with its two 
hundred and seventy miles of length and its basin of twenty-nine 
thousand square miles, proved to be too large a subject for us to 
study with equal attention to all its parts. Such a river system may, 
however, be readily analyzed into an assemblage of situations, each 
situation perhaps many times repeated in different parts 01 the area. 
