12 LABORATORY DIRECTIONS 



15. Before returning to the laboratory be sure you have 

 everything with which you started. 



REFERENCES 



Needham, Jas. G. and Lloyd, J. T. 1916. The Life of Inland 

 Waters. Comstock Publ. Co. 



Shelford, Victor E., 1913. Animal Communities in Temperate 

 America. University of Chicago Press. 



