FISHERY INDUSTRIES OF THE UNITED STATES, 1938 205 
during 1938; thus completing the study for the whole country. A full 
report covering the information obtained in this Nation-wide survey, 
showing cannery plans, illustrations, and other useful information, is 
almost finished and will be ready for publication in the near future. 
In addition to the above-mentioned investigations in the canning 
of fishery products for the home and in commercial operations, interest 
in the Bureau’s work in this field has been stimulated to the point that 
we have had to supply a rather complete technological consulting 
service to the industry on the various technical problems in fish 
canning. 
BACTERIOLOGICAL STUDIES 
During 1938 the need for expanding our facilities for bacteriological 
research became acute and, as indicated earlier in this report, the 
Bureau established at College Park, Md., a new bacteriological 
laboratory in additional space provided free of charge by the. Uni- 
versity of Maryland in its Horticultural Building on the same floor 
and across the hall from space now occupied by the Bureau’s other 
technological laboratories. The separation of the bacteriological 
laboratory unit from the chemical laboratory has been of considerable 
help in furthering the work of this unit. 
STUDIES OF ULTRAVIOLET RAYS IN KILLING BACTERIA 
This project was begun late in 1937 and a part of it has been com- 
pleted. Results on the completed portion are described in Investiga- 
tional Report No. 438, “Some Effects of Ultraviolet Irradiation of 
Haddock Fillets,’ published by the Bureau. According to the con- 
clusions in this paper, irradiation of haddock fillets for a period of 2 
minutes produced definite bactericidal effect, and irradiation for a 
period of 2 hours was found to increase the vitamin D potency of the 
fillets. Further tests are being conducted to determine the extent 
to which this process may be applicable on a commercial scale by 
experiments on more species of fish under varying conditions and 
periods of irradiation. 
STUDIES IN THE HANDLING OF FRESH OYSTERS 
As stated in last year’s Divisional report, the purpose of this investi- 
gation is to develop and recommend improved methods for handling 
fresh oysters. When oysters are first shucked, the pH is nearly 7.0, 
indicating a neutral reaction of the flesh. During the first few days 
of storage, the pH rapidly decreases until a point of approximately 
6.10 isreached. It then decreases much more slowly until it reaches a 
pH of 4.50. Below this point oysters become so sour that they are 
unfit for food. During this same period of change in the pH, the 
bacterial count declines.to a minimum, after which it begins to rise 
rapidly as a result of the increased acidity of the oysters. ‘The experi- 
ments also show that the bacterial flora changes with the acidity of 
the oysters. It was further found that excessive washing of the oysters 
with fresh water caused a loss of mineral content, in some cases from 
1.50 percent to 0.18 percent. 
