134 PLANTS WITHOUT CHLOROPHYLL 



What can Molds live On? — We have seen that black mold 

 lives upon bread. We would find that it or some other mold 

 (e.g. green or blue mold) live upon decaying or overripe fruit, — 

 apples, peaches, and plums being especially susceptible to their 

 growth. Molds feed upon all cakes or breads, upon meat, cheese, 

 and many raw vegetables. They are almost sure to grow upon 

 flour if it is allowed to get damp. Moisture seems necessary for 

 their growth. Jelly is a substance particularly favorable to molds 

 for this reason. Shoes, leather, cloth, paper, or even moist wood 

 will give food enough to support their growth. At least one 

 troublesome disease, ringworm, is due to the growth of molds 

 in the skin. 



What Mold does to Foods. — Mold usually changes the taste 

 of the material it grows upon, rendering it " musty " and some- 

 times unfit to eat. Eventually it will spoil food completely be- 

 cause decay sets in. Decay, as we will see later, is not entirely 

 due to mold growth, but is usually caused by another group of 

 organisms, the bacteria. Molds, however, in feeding do cause 

 chemical changes which result in decay or putrefaction. Some 

 molds are useful. They give the flavor to Roquefort, Gorgonzola, 

 Camembert, and Brie cheeses. But on the whole molds are pests 

 which the housekeeper wishes to get rid of. 



How to prevent Molds.^ — As we have seen, moisture is favorable 

 for mold gro^vth ; conversely, dryness is unfavorable. Inasmuch 

 as the spores of mold abound in the air, materials which cannot be 

 kept dry should be covered. Jelly after it is made should at once 

 be tightly covered with a thin layer of paraffin, which excludes the 

 air and possible mold spores. Or waxed paper may be fastened 

 over the surface of the jelly so as to exclude the spores. To pre- 

 vent molds from attacking fresh fruit, the surface of the fruit 

 should be kept dry and, if possible, each piece of fruit should be 

 wrapped in paper. Why? Heating with dry heat to 212° for 

 a few moments will kill any mold spores that happen to be in 

 food. Moldy food, if heated after removing surface on which the 

 mold grew, is perfectly good to eat. 



* An experiment to show conditions unfavorable for growth of molds should be 

 shown at this point. 



