Explanatory Ifote 



The series embodies restilts of investigations, usiially of restricted scope, 

 intended to aid or direct management or utilization practices and as guides for adminl- 

 str.itive or legislative action. It is issued in limited auantities for the official use 

 of Federal, State or cooperating agencies and in processed form for econony and to avoid 

 del.oy in publication. 



Washington, 0. C. 

 May 1950 



