188 ILLINOIS STATE ACADEMY OF SCIENCE ' 



a pipe at the rate of about 13 pints a minute became 

 station II. The area is only a few feet wide and is clear, 

 fresh water, the bottom being covered with dead grass 

 and other vegetable matter. (Ill) A station at the north- 

 west corner of the area called the muskrat region is 

 Station III. There the shallow stream flows slowly un- 

 der a bridge. The station is a mud bottomed one with 

 a few bricks near the bridge. (IV) This station is lo- 

 cated at the outlet which is west of Station III. Here 

 the water flows rather swiftly through two large pipes 

 which are beneath the street car track. Here are found a 

 number of large stones, two large cement blocks and a 

 floating log. (V) This area is of sluggish water which 

 flows from a tile on the east side of the little road. This 

 station is located just north of Station III. The water 

 is rich in algae. In places it has a film due to a certain 

 kind of bacteria. 



In studying animals as they exist in nature, one can- 

 not overlook the fact that conditions of environment 

 have much to do with the life of any region. Animals 

 of a pond are influenced by such physical factors as the 

 character of the surrounding country, the movement and 

 the depth of the water, the character of the bottom and 

 of the shores, and the light, temperature, and winds. 

 Furthermore, animal life is influenced by such chemical 

 factors as the acidity or alkalinity of the water and the 

 presence of gases, salts, etc., in the water. Food and 

 biological environment also affect pond life. The sur- 

 rounding country is rich land of a glaciated region. It 

 would seem, then, that a large amount of food materials 

 might be carried into the lake by the contributing 

 streams. There are small hills near, and a small patch 

 of timber, thus limiting the effect of winds. Winds have 

 a decided effect upon the life of a lake for they keep the 

 water moving. In the rainy season of March and April 

 the water is high and the inflowing stream is rapid. But 

 in the dry season of mid-summer there is only a trickle 

 and the lake is very low. The pond bottom is largely 

 muck composed of decayed animal and vegetable debris. 

 This muck is quite deep, for one sinks in it several feet. 



