PROGRESS IN BIOLOGICAL INQUIRIES, 1937 55 



terested in particular pollution problems have been sent out ; and un- 

 derstanding of the actions of industrial pollutants, particularly of dye 

 wastes, pulp and rayon effluents, petroleum waters and mine waste has 

 been materially advanced. The voluntary cooperation of many manu- 

 facturers in the practical application of these findings to definite poll-u- 

 tion problems and in the following of recommendations for tlie elimi- 

 nation of pollution nuisances has been most gratifying. 



This year's work has carried the pollution survey into several new 

 States so that every State in the Union and all of tlie important river 

 systems have now been included in the investigations. The hold .vad 

 laboratory work has been completed for the second part of the pol- 

 lution bulletin. 



The basic physiological studies of salmonids, bass, and catfish on 

 which the applications of the pollution analyses and assays are made 

 have been continued and extended to include the physiological re- 

 actions of fishes of these three groups to the minute quantities of the 

 less abundant substances present in stream, lake, and impoimded 

 waters. Extensive experimental tests utilizing special apparatus de- 

 veloped for these physiological studies have been carried on through- 

 out the year and are still in progress at the Columbia laboratories, 

 and as a part of this work large series of catfish are being main- 

 tained under experimental conditions at Ft. Worth, Tex., by cwo 

 members of the staff of this unit. 



These physiological experiments have directed attention to the cumu- 

 lative eifects of prolonged exposures to very small quantities of sub- 

 stances which are ap])arently without immediate action on the fish. 

 The tests with fluorides, for example, which are found in small quan- 

 tities in many waters in the southwest, have shown that continuous 

 exposure to even small quantities of these salts as found in some of 

 the southwestern streams produces definite detrimental changes in the 

 reproductive system and in the musculature of the fish, thereby impair- 

 ing both the fertility of tlie fish and the quality of its flesh. Technical 

 publications on these salts and several others will appear soon. 



Tlie field work correlated with these physiological studies of indi- 

 vidual fish has involved the investigation of bog- fed streams, streams 

 of glacial origin, mountain streams, and western impounded waters. 

 Detailed surveys of tlie waters of Elephant Butte Reservoir, Lake 

 Mead, and several of the smaller western impoundments were made 

 during the summer in cooperation with a committee of the National 

 Research Council and definite investigational programs were initiated 

 at Elephant Butte and Lake Mead. This work was then continued 

 in several western streams, including the Colorado, Columbia, and 

 upper Missouri systems. Although not yet completed, practical appli- 

 cations of these studies have already appeared in connection with the 

 stocking programs of various western streams on which impound- 

 ments are being built or are contemplated, and explanations have been 

 obtained concerning the unproductiveness of certain reservoirs and 

 streams in these regions. Twenty-fi\-e sets of analyses and assays have 

 been made already for Federal and State officials to determine the 

 suitability of waters from various springs, wells, and impoundments 

 for fish or for fish hatchery purposes, in view of the physiological 

 findings now available. Special equii:)ment, not available heretofore, 

 has been devised for the mobile field laboratories, and some of the 

 physiological studies of the fish can now be made in the field. 



