162 BACTERIA, YEASTS, AND MOLDS 



cream ; for preventing hams or bacon from molding or 

 becoming slimy, the borax may be dusted on the surface, 

 not more than one quarter of an ounce being used for 

 each pound of meat. 



But any one of these materials, if used in considerable 

 quantity, is certainly injurious, and this fact makes it 

 quite out of the question to recommend them for home 

 use. It is quite impossible for the physician, much less 

 the housewife, to know how much may be used without 

 danger. 



NONPOISONOUS PRESERVATIVES 



In protecting food by preservatives we are not confined 

 to poisons, since there are a few materials capable of pre- 

 serving food that are not poisonous but are, on the con- 

 trary, beneficial to us. The use of such preservatives is 

 of course perfectly proper. Some of them have been in 

 use for many years and at the present time are more used 

 than ever. The chief ones are mentioned below. 



Sugar. As already indicated, bacteria do not grow 

 readily in pure sugar solutions, and if the solutions are 

 very strong they do not grow at all. The other forms of 

 microorganisms also, molds and even yeasts, fail to grow 

 readily in solutions containing a considerable quantity of 

 sugar. It is therefore quite feasible to preserve many 

 of our foods from putrefaction by simply mixing them 

 with a considerable quantity of sugar. Since sugar is an 

 excellent food for man it does not injure the material but 

 increases the food value of the product. As a preserva- 

 tive sugar has more value against bacteria and molds than 

 against yeast. It is the material which readily supports 



