No. 2(l92l) REMARKS ON CANNING 37 



fish, causing decay and putrefaction, a wonderful and wholesome 

 provision of what we call ' Nature ' for the disintegration of 

 lifeless organic matter. They are so excessively minute that 

 thousands can pass through an orifice as small as the point of the 

 finest needle, while their multiplication is so rapid, usually by 

 fission, that a single bacterium may easily become a thousand 

 within 6 hours. Especially is multiplication rapid when tempera- 

 ture, moisture, and the nidus (breeding place) are suitable. It so 

 happens that bacteria flourish and breed best between, roughly, 

 70° F. and 100° F., and this range of temperature, or the bacterial 

 optimum, is precisely that found in India and the tropics during 

 the greater part of the year; on the humid coast the element of 

 moisture is specially favourable. Consequently, as experience 

 shows, putrefaction in the Indian sea coast climate is enormously 

 rapid, so that fish, which is more readily susceptible of putrefaction 

 than meat owing to the less solidity and consequently more ready 

 penetrability of its tissues, rapidly taints. Hence the tissues of 

 meat and fish, etc., especially in India, are. within a few hours, full 

 of putrefactive bacteria. 



6. Fortunately these minute vegetable organisms are more or 

 less paralysed by temperatures slightly above 100° and below 

 60° F., while as a rule they are entirely destroyed by a temperature 

 of or slightly higher than 170 or l8o° F. which is the general 

 ' pasteurising ' or sterilising temperature. Hence organic matter 

 such as fish is sterilised as soon as every portion of the tissues is 

 raised to this or a somewhat higher temperature, or in other words, 

 cooked. But since the air is laden with similar bacteria, the fish 

 are again attacked by them as soon as the temperature of the 

 tissues falls below the above point, that is soon after they are 

 removed from the cooking stove. Hence while fully cooked fish 

 remain untainted longer than when uncooked because the bacteria 

 have been wholly destroyed, they gradually taint by the action of 

 fresh swarms of bacteria. Consequently to keep fish continuously 

 and permanently from taint they must, whether previously sterilised 

 or not, be placed in containers and hermetically sealed up, so that 

 no air with its accompanying bacteria can have access to the fish, 

 and the container with its contents must then be submitted to a 

 full sterilising temperature (usually — for fish, meat and vege- 

 tables—that of or above 212^ F. or boiling point) until the whole of 

 the contents, to the very centre, have attained that temperature. 



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