20 BULLETIN 908, U. S. DEPARTMENT OF AGRICULTURE. 
viscera, which harbor the bacteria producing spoilage, are removed 
before an advanced stage of decomposition has been reached. 
SWELLS. 
During the latter part of the season of 1913 reports reached the 
laboratory of trouble due to swells at a few of the canneries on the 
west coast. No cause for this condition could be found by those in 
charge of the canneries, and, in spite of all the precautions taken, it 
increased each year, until it was estimated that as much as 30 per 
cent of the pack of one or two factories had swelled during the season. 
Canners in other localities reported that they had about 1 per cent of 
swelis in a season’s pack, though more were found in some seasons 
than in others. As it was felt that more trouble was due to swells 
than the majority of the packers were willing to admit, a special 
investigation was undertaken to determine the cause. 
At the close of the sardine packing season of 1913, an investigation 
on the canning of clams was made at the Eastport laboratory during 
which gas-producing, facultative anaerobic bacteria were found in 
canned clams processed under commercial conditions.t A tempera- 
‘ ture of 240° F. was required to destroy the spores of this organism, 
which suggested the possibility that this organism, or one of similar 
nature, might be responsible for swells in sardines. 
it was first planned to carry on the experimental part of the work 
at local pomtis reporting the greatest number of swells. After the 
work was under way, however, statements from canneries along the 
whole coast indicated that the trouble was more general than aé first 
supposed. In one case a canner reported that a large percentage of 
goods stored in his shipping room were ‘“‘swells.” Another canner 
reported the finding of a large quantity of ‘‘swells” in a shipment 
made by boat to the Pacific coast. The reports in these cases were 
accompanied by samples of the “swelled” goods. Bacteriological 
examinations of cans received from these canneries, as well as of 
cans of swelled sardines secured from packers which would be fairly 
representative of the whole Maine coast, showed the presence of an 
anaerobic organism in pure culture. It was then decided to extend 
this part of the investigation to the entire coast. 
The bacteriological part of the work was begun durimg the late 
fall of 1915 and continued durimg the early fall of 1916. As it pro- 
gressed it became apparent that the organism that was being studied 
as a cause of swelled cans was also probably responsible for the 
decomposition of the feed of herring, and, therefore, indirectly for the 
characteristic belly breaking of feedy fish. A more extensive study, 
including both chemical and bacteriological work, was therefore 
conducted during the early fall of 1916. 
1 Unpublished reports in the Bureau of Chemistry. 
