724 Reading-Course for Farmers' Wives. 



Bacteria are destroyed by heat. — All bacteria are promptly killed by 

 heat unless they are in the spore form or resting stage. There are resting 

 stages of =ome of these organisms when the conditions for active life 

 are unfavorable. The organism itself may dry up and assume a dormant 

 form, and resume its active form again when favorable conditions occur ; 

 or it may throw off spores. Spores resist heat far better than the active 

 or vegetable organism, so although we may have used enough heat to 

 kill the active forms we cannot be sure that we have destroyed all 

 organisms unless we know that the particular organism which we seek 

 to exterminate does not form spores or is not in the spore stage. Boiling 

 for twenty minutes will generally but not always kill most forms, in- 

 cluding the spores. Water is pronounced safe when it is thus boiled. 

 Mere simmering of water is not sufficient. 



Fresh air and sunshine are great antidotes. — Direct sunshine kills most 

 bacteria. Many persons are afraid to take fresh air and sunshine in 

 sufficient quantities to counteract the bad influence of dark rooms, of 

 moisture and of poor air, and yet of all the bactericides known there is 

 none which compares in effectiveness to sunshine. Much suffering would 

 be saved if persons could only be brought to a realization of this fact. 

 Airing and ventilating bed-rooms, kitchens, cellars and stables aid much 

 in keeping them wholesome. 



Drying. — About thirty per cent moisture is required for the growth 

 of bacteria. This fact is the principle in the preservation of many of 

 our foods. To preserve seeds we dry then; and they do not begin to 

 sprout until they have been moistened at the time they are needed. 

 Flour is practically free from decomposition because it is dry, and 

 crackers keep indefinitely for the same reason. In some sections, tons 

 of fish are prepared for market by drying. Fruits such as berries, 

 laisins, apricots, currants, prunes, and apples are preserved in this way. 

 Dried beef has long been a famiHar example of this principle. It must 

 be remembered that drying only arrests the growth of bacteria and when 

 food has over 30;^ of moisture there is danger of its spoiling. Dried 

 foods are therefore kept in a dry place to prevent absorption of moisture 

 and consequent spoiling. 



Cold storage. — As a means of preventing putrefaction and decay, 

 store-houses are cooled artificially and a low and constant temperature 

 maintained. Eggs, fruit, vegetables, etc., may be kept for a consider- 

 able period of time if they are frozen, and may then be delivered at the 

 market in fair condition for use. There is some question, however, re- 

 garding the safety of the use of cold-storage foods, for food deteriorates 

 quickly if it is taken from cold storage and may not always be used imme- 



