56 U. S. BUREAU OF FISHERIES 
Culture, an experimental hatchery is under construction at the Quil- 
cene, Wash., station. This unit is expected to be in operation early 
in 1987 when the studies on disease prevention and control will be 
resumed. 
The apparatus for prolonged dipping, which consisted primarily 
of a calibrated floating siphon, has been materially simplified. The 
modified type of apparatus has been in regular use at two hatcheries 
for the past 7 months and the hatchery personnel report it to be far 
more satisfactory than the earler type. Both hatcheries have been 
applying malachite green in a 1: 450,000 concentration to all fish and 
report definite success although accurate figures are not available. 
During the months of May, June, and July, various hatcheries in 
the intermountain district were visited to observe the conditions and 
equipment and to confer with hatcherymen on their disease problems. 
Experiments on the susceptibility of B. salmonicida to common 
hatchery disinfectants and to moist heat showed that a 1:10,000 
solution of potassium permanganate will kill the bacteria im less than 
10 minutes. With copper sulphate at the same concentration between 
30 and 60 minutes were required to accomplish the same result. The 
most efficient disinfectant was “HTH” which, in a 1: 100,000 solution, 
killed the bacteria in less than 10 minutes. The bacteria were found 
to show little resistance to moist heat, being killed in less than 1 
minute at 54° C. On the basis of these experiments it 1s recommended 
that hatchery equipment be sterilized by placing in hot water at 
55° C. or, in the absence of considerable organic material, in a 
1: 100,000 solution of “HTH” for 10 minutes. 
Field studies on the occurrence of furunculosis among loch leven 
trout in Lake Madison, Mont., were undertaken during November and 
December. Cultures were made from the kidneys of adult fish by 
Dr. C. J. D. Brown of Montana State College and forwarded to 
Seaitle for identification. Of 77 cultures taken at the Lake Madison 
traps four were found to contain B. salmonicida. This indicates that 
furunculosis was not as prevalent during 1936 as it was reported to 
be during the previous year. 
The disease service has proved very popular and a large number 
of specimens submitted by various State and bureau hatcheries and 
by private individuals were examined at both the Washington, D. C., 
and Seattle laboratories. Although in most cases the service is neces- 
sarily limited to the examination and diagnosis of preserved specimens 
it has proved very helpful in enabling fish culturists to adopt proper 
control measures. 
INVESTIGATIONS IN INTERIOR WATERS 
Dr. M. M. Extis, in charge 
POLLUTION STUDIES 
During the past year investigations concerning the toxicity of in- 
dustrial effluents on aquatic life have been continued in 22 States so 
that to date some 60 major groups of effluents representing over 200 
kinds of industrial wastes have been studied, assayed, and their com- 
ponents standardized. For many of these substances detoxifying 
procedures have been devised and tested. From these data on 
