PROGRESS IN BIOLOGICAL INQUIRIES, 1938 73 
in previous years. One very gratifying feature is that some of the 
hatcheries have ceased to be steady clients of the service, which 
would indicate that the common diseases are now under better 
control. 
Dr. Davis spent some time at the York Pond (N. H.) station in 
connection with an outbreak of furunculosis. In an effort to eradi- 
cate the disease the trout were either removed or destroyed and the 
ponds and hatchery disinfected with chlorine and hydrated lime. 
Owing to the nature and extent of the ponds this was a very difficult 
task but it is believed that it was accomplished successfully. 
INVESTIGATIONS IN INTERIOR WATERS 
Dr. M. M. E tts, in charge 
POLLUTION STUDIES 
Headquarters for the pollution studies have continued at Columbia, 
Mo., where the University of Missouri has courteously provided 
laboratory space and facilities. A subsidiary laboratory at Fort 
Worth, Tex., has also been maintained. The various phases of the 
pollution investigations are so organized that they contribute to the 
central purpose of determining the suitability of particular waters 
both in the stream and in the hatchery for different types of fishes, the 
detrimental action of many substances which enter streams or water 
supplies either naturally or through pollution, and reliable means 
for measuring the condition of the fish themselves. In this work 
cumulative effects and impairment of vital functions are receiving 
more attention than the immediate lethality, as the former are both 
more insidious and far reaching than the latter. 
Three major lines of investigation are in progress at the Columbia 
field unit and the Fort Worth Laboratory. 
Analytical studies—Waters, muds, and aquatic organisms col- 
lected in the field are sent to the central laboratory for detailed 
analysis. Determination of these samples is carried out by Dr. B. A. 
Westfall and assistants. In addition to the materials collected in the 
course of field work conducted by the staff, a large number of samples 
are sent in for analysis by the various State agencies. 
Bioassays.—The specific effects of materials found in waters, muds, 
and pollutants, on living fish and other aquatic animals, are deter- 
mined by the bioassay method. The bioassays of pollutants sent to 
the Columbia unit by State authorities and other sources have grown 
to be an important activity of the laboratory, with 50 to 200 such 
assays constantly in progress. Equipment and procedures have been 
so standardized that it is possible to assign a considerable portion of 
this work to analytical assistants who carry on these tests as routine 
tasks. 
Physiological investigations——The underlying causes for the ac- 
tions of the various substances found in natural waters and _pol- 
lutants on living fish are sought throngh studies of the physiology 
of fish. This phase of the work is under the direct supervision of 
Dr. Ellis and is conducted both in the Columbia Laboratories and 
at Fort Worth. A major field of physiological investigation during 
the year was a study of the effects of various components of larva- 
cides and herbicides on fresh-water fishes and associated aquatic food 
