Explanatory Nate 



The series embodies results of iriTestigationSj usually of restricted 

 scope_, intended to aid or direct management or utilization practices and 

 as guides for administrative or legislative action„ It is issued in 

 limited quantitiea for the official use of Federal^ State or cooperating 

 agencies and in processed form for economy and to avoid delay in publication. 



Washington J D, C. 

 May, 1951 



