26 U. S. BUREAU OF FISHERIES 
and the livers of various fish including cod and related species, halibut, 
swordfish, and California tuna. Many of these experimentally pre- 
pared products were chemically preserved at sea and forwarded to 
our College Park laboratories for tests. These samples were tested 
bacteriologically for evidence of decomposition and the finished 
products, such as oil and meal, were tested chemically and nutritionally. 
It has been found that certain of the volatile aldehydes, particularly 
acetaldehyde, readily sterilize the raw material and may be removed 
by the application of heat in the conventional rendering process. It 
has also been found that on the application of heat through material 
preserved in some of the aldehydes, the material becomes increasingly 
firm, thus reducing to a considerable extent the softening action of 
cooking ordinarily encountered in the rendering of fish waste. 
In view of the progress being made in the United States and abroad 
looking toward the utilization and preparation of special glandular 
and pharmaceutical products from the vital organs of fish, the above 
cooperative arrangement was extended to include some preliminary 
studies in that field. Entrails or vital organs of cod or related species 
preserved at sea were received at the laboratory and segregated 
according to organs. The initial work was confined toa study of the 
pyloric caeca and the male gonads. The work on pyloric caeca was 
in the nature of a continuation of similar studies done by W. W. John- 
ston of the Biological Board of Canada. Mr. Johnston discovered 
that the pyloric caeca of fish, when promptly dehydrated, are excep- 
tionally effective as bates for tanning of leather. The object of our 
experiments with pyloric caeca was to determine whether chemically 
preserved pyloric caeca may be used in the production of bates in the 
same manner as fresh pyloric caeca. The difficulty in the handling 
of this product heretofore has been that some trouble was encountered 
in dehydrating this material at sea on commercial fishing vessels. 
Preliminary work on male gonads has been undertaken for the purpose 
of determining whether protamine may be produced from the chemi- 
cally preserved raw material. The difficulties of producing protamine 
from the raw material at sea have been substantially the same with 
respect to dehydration of the raw material, as was encountered in 
the production of bates for tanning from pyloric caeca. 
Although the above-described phase of this cooperative project on 
the utilization of fish organs is in a preliminary stage, it is anticipated 
that, with the finding of new and useful products obtamable from the 
various organs, it will be profitable for the cod and haddock fishermen 
to save the entrails and other vital organs now discarded at sea. Up 
to the present, it has been customary for the fishermen occasionally 
to save some of the livers and it is now hoped thatit can also be made 
profitable to fishermen to save other vital organs as well. 
NUTRITIVE VALUE OF AQUATIC PRODUCTS 
The importance of conducting studies of the nutritive value of 
aquatic products is readily recognized when it is realized that the 
fisheries constitute a basic food industry. For this reason food research 
is the major part of the Bureau’s technological investigations. Not 
only is it necessary to determine the fundamental chemical composition 
and nutritive value of aquatic products as a foundation for truly 
evaluating their economic and dietary importance; but nutrition tests 
constitute the only true yardstick or standard of measurement for 
