190 DEPARTMEyT OF THE NAVAL SERVICE 



8 GEORGE V, A. 1918 



Swelled Cans. — Outwardly the cans vary from a sliglit " bulged " appearance to 

 a more pronounced swelling. The top and bottom are forced out as a result of the 

 pressure, and present a decided convex surface. As the swelling becomes greater the 

 oil or sauce will be forced out between the soldered parts of the can, and in pronoun- 

 ced cases the outside surface is greasy and wet, and possibly covered with the oil or 

 sauce. Swelled cans, when shaken, have a characteristic " rattle " on account of the 

 extra space within, resulting from the swelling. When the cans are opened, gas is ex- 

 l>elled, accompanied in advanced swellings by portions of the liquid contents. In ad- 

 vanced cases there is a tendency for the oil or sauce to pour out over the surface of 

 the cans. 



The condition of the contents varies considerably. Usually the fish are macerat- 

 ed, disintegrated, and soft, and are intermixed with the oil or sauce; they have lost 

 their entity. The odour is variable, — frequently it is not unpleasant, resembling to 

 an accentuated degree the natural smell of normal sardines. In other instances a 

 pronounced putrefactive odour is evident. It may be that the putrefactive odour is 

 present at all times and is masked by the spices or other ingredients of the sauce. 

 That is a point which can only be definitely pronounced upon after a more extended 

 investigation. 



CANS EXAMINED. 



Up to the present I have examined forty cans, normal and swelled. The cans 

 have been obtained personally or by express: 



(1) direct from various canning factories in the province of New Brunswick and 

 in the State of Maine, U.S.A. 



(2) Erom the Health Department of a city in the Maritime Provinces. 



(3) Erom retail grocery stores. 



Many of the normal cans, representative of the various factories, proved to be 

 sterile; from some have been isolated spore forming bacteria, inactive on fermentable 

 carbohydrates,— see page 211, Culture 21 and in no instance have gas producing 

 organisms been found. 



Erom certain of the swelled cans I have isolated a variety of strains of gas pro- 

 ducing bacteria, none of which show evidence of spore formation. The cans from 

 which these strains have been isolated are representative of three of the factories 

 engaged in canning; and for the sake of clearness these factories have been specified 

 as Pacher A, Packer B, and Packer C, respectively. Eurther, from swelled cans I have 

 also isolated strains of bacteria which fail to ferment any of the carbohydrates used 

 as test substances (pages 212-213). It remains, therefore, to be added that from some 

 cans apparently " swelled " I have failed to isolate gas producing bacteria. 



As already stated (page 185) the organisms isolated from the various sources have 

 for the sake of convenience been arranged in two main classes : — 



Class I. — Gas producers. 

 Class II. — Non gas-producers. 



The gas-producers (see pag-es 192-207) have been isolated solely from swelled cans 

 ■ I sardines. Of the swelled cans examined the majority were obtained from sources 

 ;. and 3 (page 190). Some were submitted by source 2. Under the circumstances it 

 has seemed desirable to use some means of differentiation. Accordingly the swelled 

 cans obtained: (1) from the canning factories, and (3) from retail grocery stores have 

 been designated "Swelled cans, Series 1"; those submitted by (2) a certain City Health 

 Department, "Swelled Cans Series II." 



