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 

 swells 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 sardme 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. 1 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 points 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 at 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 during the late 

 fall of 1915 and continued during 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. 



