REPORT OF THE SUPERINTENDENT OF THE BIOLOGICAL STATION, 
To the Director of the Laboratory. 
Sir: The past two years have offered new and interesting 
conditions in the environment in which the work of the Illinois 
Biological Station has been prosecuted. The period of 1894 
and 1895 was one of typical low water, without an extensive 
rise of the river during the spring and early summer, when such 
floods usually occur. On the other hand, these years were not 
marked by long uninterrupted periods of very low water. Under 
these conditions of two years of generally low water, without 
marked fluctuations, the lakes were thoroughly choked with 
vegetation, and even the banks of the river itself became fringed 
with a rank aquatic growth. A rise to 12.6 feet, culminating 
January 6, 1896, was succeeded by a series of minor floods at 
intervals of about two months throughout the year. The net 
result was an increase in the average height of the river for the 
year, which was 6.87 feet above low-water mark—fully two 
feet above that of the average for the two years preceding. 
This was, then, a high-water year, without marked fluctua- 
tions, and the result was that the vegetation remained to 
a considerable extent in the lakes and the river. The year 
1897 opened with rising water, which culminated J anuary 23 at 
12.9 feet, while a subsequent rise on March 27 reached a height 
of sixteen feet—the highest point attained since 1892. (See 
Plate II.) From this maximum the river fell slowly through 
the four months that followed, reaching a minimum early in 
August. From this time until the close of the year, in conse- 
quence of a general drought throughout the State, low water 
persisted, there being only a slight rise as evaporation was 
checked during the cooler weather of autumn. In spite of 
the long-continued low water the average height for the year 
was 6.9 feet—a slight increase over the preceding year. There 
was thus present the somewhat unusual condition of long- 
continued high water during the first half of the year followed 
by an uninterrupted period of unusually low water in the” 
second half, the change from the one to the other being quite 
abrupt. Under these circumstances the vegetation was largely 
removed or its excessive growth prevented. The contrast 
