CANNED SARDINES 107 



a few days the cans which had been thus infected were definitely "swells," having all 

 the appearances of the original swelled cans upon which the work was begun. On 

 opening the cans the contents presented the characteristics of the contents of the 

 original cans. The material was examined, and bacteria secured which proved to be 

 "identical with the bacteria injected into the cans at the beginiling of the experiments. 

 The bacteria isolated from swelled canned sardines and injected into normal cans of 

 sardines had produced typical swells; and from the experimental swells, bacteria had 

 been secured which were identical with those originally isolated. Thus the "Rules of 

 Proof" currently relied on by investigators, have been satisfied. As a result of these 

 experiments we have the proof that '' swells " are produced by bacteria ; and that the 

 bacteria isolated during this investigation are some of the bacteria which are responsible 

 for " swells " or " blown canned sardines." 



Significance of the Bacteria Isolated. 



It is desired to keep this paper as free as possible from technical terms, but some 

 reference must be made to the significance of the bacteria isolated from the cans of 

 sardines. Although eight definite strains of organisms capable of producing gas were 

 isolated or secured, they may all be divided broadly into two main classes: 



I. The cla^s of bacteria commonly associated with putrefaction of foodstuffs, and 

 the putrefaction of organic matter generally. — Two of the strains i-ecovered are in- 

 cluded here; and in the scientific report, already mentioned, have been classed as 

 belonging to the group or type Bacillus vulgaris. There are many organisms to which 

 this name is given, and they will frequently be fovmd in stagnant water, and in cases of 

 putrefaction or rotting as already stated above. In connection with cases of food poison- 

 ing, some investigators have found large numbers of these bacteria in the particular 

 food suspected of being the cause of the poisoning. In the absence of feeding experi- 

 ments it is impossible to say whether or not the organisms isolated by me from sardines 

 would have caused poisoning had they been eaten. The only statement which can be 

 made with safety, is that bacteria having indentical characteristics have been found 

 by some investigators in cases of food poisoning; and the investigators concerned have 

 been strongly of opinion that such organisms were the responsible agents. 



II. The bacteria which are searched for in all cases of water and milk pollution 

 as an, index of contamination due to fceces or manure. — There are very many varieties 

 of these bacteria, but they are commonly classed under a general heading as the colon 

 group; the specific name being Bacillus coli. Six of the strains of bacteria recovered 

 in this investigation are members of the colon group, and that fact is one of consider- 

 able import. The original Bacillus coli was isolated in 1885, from the intestines of a 

 sick child. Organisms which are common in the intestinal tract are designated as 

 frecal organisms. And, just as we have these in the human intestines, so also are they 

 to be found in the intestinal contents of cattle : for this reason, when milk is suspected 

 of being unclean, and unfit for human consumption, particularly if the supply is being 

 used for babies, it is necessary to examine samples of such milk for organisms of the 

 colon group. Certain varieties of this group are also fovmd in soil, on grains and in 

 dust; these may have come immediately from manure, or they may have lived for 

 several generations in their new home. Of the colon bacteria secured from the cans of 

 sardines, the laboratory tests would suggest that some have been derived immediately 

 from faeces or intestinal contents ; others woi;ld appear to have come from a less object- 

 ionable source. As to whether they all came originally from faeces, I cannot say. The 

 bacteria which suggest intestinal contamination may have been in the viscera of the 

 fish before packing, or may have been added during the packing by unclean hands of 

 workers. If they were in the intestines of the herrings, and this is probably the more 

 likely source, it is important that packers should know "whether or not the feeding 

 ground of the fish, and the location of the weirs are subject to contamination from 

 sewage. 



