36 MADRAS FISHERIES BL'LLETIN VOL. XIII, 



for the varied products of their several localities, coupled with the 

 possibility of supplying those demands by the advance of science 

 applied to industry and by facilities for cheap transport. The fish 

 of the coasts can be brought thousands of miles into the interior ; 

 the fruits and vegetables of one locality can be exchanged for 

 those of others, or those of favoured regions, such as California, 

 can be sent to the most distant parts of the world ; surplus stocks 

 of edibles grown or obtained in abundance during the summer can 

 be stored in immense variety and attractive condition for the 

 support and solace of winter months. Until canning (and later on 

 mechanical refrigeration) was discovered, foods of a perishable 

 nature were either not grown except for local needs, or were thrown 

 away, or were cured — fish for instance — by methods such as salting, 

 hard drying, smoking, etc., which preserved them indeed but only 

 as articles not always palatable or even digestible, and which 

 lacked the variety, savour, and succulence of natural products. 

 Hence canning speedily met with favour, especially when steam 

 brought cheap and rapid transport to the aid of enterprise. 



What canning is and means. 



4. Simply, canning is a method by which perishable goods can 

 be kept almost indefinitely in closed containers from decay and 

 deterioration, and even rendered more attractive to the palate, more 

 rapidly digestible, and safer to the health than the raw product. 

 More fully and scientifically described it is a method by which all 

 classes of putrescible or fermentible products such as meat, fish, 

 milk, fruits, vegetables, are packed in containers, usually of tin 

 plate or glass, hermetically sealed so as to prevent the access of 

 bacteria, and then, whether previously sterilised or not, finally 

 sterilised by the action of heat to a degree which destroys all 

 bacteria within the container, so that if the container is absolutely 

 air-tight, putrefaction or fermentation is no longer possible. 



5. The rationale of canning will be understood by a perusal 

 of the chapter on putrefaction in the hand-book of fish-curing 

 issued as a Fisheries bulletin. Briefly and simply it is this: the 

 air swarms with minute vegetable organisms called bacteria which, 

 according to their character, are the active causes of putrefaction 

 and fermentation, while certain classes cause disease. These 

 putrefactive organisms are comparatively powerless against living 

 bodies, but instantly attack non-living materials such as meat and 



