184 DEPARTMENT OF THE NAYAL SERriCE 



8 GEORGE V, A. 1918 



minutes placed in flowing steam; dried in room through which hot air is continually 

 circulated, for 1 hour; heads discarded and the remainder of the fish arranged in the 

 cans; oil automatically added, and tops put on, and fastened by either the "rolling'' 

 or the " pressing " process. The cans are then heated as specified above. In some fac- 

 tories the preliminary steaming for 10 minutes is dispensed with, and a continuous 

 progression through a bath of cottonseed oil at a temperature of 200° C. is substituted, 

 this occupying 2 to 3 minutes. 



In one factory where the fish are fried in oil for 3 minutes or so, the final heating 

 is done under pressure at a temperature of 225° F, for a shorter period. 



It should be added that in all the sardine factories visited, the most careful super- 

 vision is exercised in the final packing of the cans in cases before shipping. Each 

 individual can is rapidly passed through the hands of an expert "tapper" who discards 

 cans displaying any irregularity, such being reprocessed or entirely discarded. 



The project of the investigation may be logically stated thus : "Essentially to deter- 

 mine whether or not the swelling of the cans is due to the activities of bacteria." If 

 on examination, and when submitted to suitable cultural methods strains of bacteria 

 are isolated, the procedure to be as follows : — 



1. Purify and obtain in pure culture. 



2. Determine the morphological, biological and biochemical characteristics 

 of the organisms. 



3. Inoculate the strains obtained in pure culture into normal cans and 

 record condition at stated intervals. 



4. Treat "control" normal cans in a similar manner except for the inocula- 

 tion with the culture. 



5. If swelling occurs in the inoculated cans, and no change is noted in the 

 " control " cans, the presumption is raised that the swelling is due to the organ- 

 isms used for inoculation. 



6. Examine the "swelled" cans and determine in culture the presence or 

 absence of bacteria. 



7. If bacteria are found, purify and compare culturally with the strains 

 used for inoculation. 



8. If on comparison the strains be found culturally identical with those 

 used for inoculation the cause of the "swelling" has been established; and experi- 

 mental proof has been obtained to Avarrant the statement " that the swelling of 

 the cans is due to the activities of bacteria." 



The data recorded in this report show that up to this point, the work has been 

 successfully accomplished in so far as concerns certain strains of bacteria; and the 

 " Postulates of Koch " have been satisfied. 



While at the biological station, I not only visited the factories as already stated, 

 but many swelled cans of sardines were secured, and a number of organisms in the 

 cans isolated in culture. An attempt was also made to discover the source of the 

 organisms. Samples of sea water taken from the weirs, samples of oil and tomato 

 sauce as used in the packing, intestines of fresh herrings, and the excreta of herrings 

 were obtained. IvTo organisms were found in the oil; the tomato sauce in sealed recep- 

 tacles as imported from Italy has still to be examined; but from the sea water, herring 

 intestines, and herring excreta several strains of bacteria were isolated. These, with 

 those I found in the sardine cans, I brought back on my return to the laboratory here. 

 During the succeeding months a number of the cultures have died out, and those 

 remaining from sea Avater, herring intestines, or excreta, fail to produce gas in 

 carbohydrates. 



