PAPERS ON BIOLOGY AND AGRICULTURE 163 



AN ECOLOGICAL SURVEY AND FLOEA OF 

 LAKE KNOX 



Paul K. Houdek. Knox College 



This is a first report of an ecological survey being 

 conducted on a small area containing a pond and a 

 swamp, near the eastern limit of Galesburg, Illinois. 

 This work was begun late in the fall of 1921 in conjunc- 

 tion with a zoological survey by Miss Florence Adcock, 

 which was published in the last year's proceedings of this 

 organization. 



The lake lies in a triangular area formed by two 

 embankments of cinders and rubbish. These embank- 

 ments lie, one parallel to and the other at right angles 

 with the axis of the broad ravine between the surround- 

 ing low hills. The lake itself is roughly triangular in 

 shape, being 380 ft. long and 210 ft. wide at the east end. 



Lake Knox originated about forty years ago. and 

 until about 1911 was used to supply water to a nearby 

 brickyard. Fntil it was abandoned, it was kept clear of 

 any great amount of plant life. 



The marsh lies directly east of the lake, across the em- 

 bankment. The marsh area is about 200 ft. square and 

 receives most of its water supply from Lake Knox. The 

 development here has been rather rapid. I can remember 

 fishing here about six years ago. 



The main volume of water entering the lake comes 

 through a creek from a similar lake to the south. A near- 

 by spring also contributes its water. The overflow drains 

 eastward into the marsh through two drains, the more 

 recent of which caused the lowering of the lake by about 

 eight inches. Except for the spring deluge and an occa- 

 sional summer drouth, this area has a fairly constant and 

 abundant water supply. 



This region has been used for years as collecting 

 ground for both Knox College and the High School Bi- 

 ology departments. It furnishes frogs, fish, turtles, 

 snakes, crayfish, snails, a few bivalves and numerous pro- 

 tozoans, such as paramecia. vorticella, euglena and 

 amoeba. Filamentous water plants and weeds have been 

 collected here also. 



