Domestic science (Johnson, for schools and homes)

Dust Plants grow from tiny seeds, or germs, that float in the air as dust. They are classed as moulds, yeastt, and bacteria. Moulds are fungi of considerable size, easily visible to Fig, 1. the naked eye, composed of thread-like tubes. Some arc ■white, some blue, green, brown, black, or red They grow 22 COOKING 23 upon all kinds of material and have a variety of forms. They grow and multiply rapidly in warm, moist places, and destroy food, clothing, etc. Mildew is a form of mould. Moulds begin to grow on the outside of food, as bread, cheese, etc., and branch out and grow down into the food, like the roots of a plant. Rotting is only the process of mould growth. To prevent mould, protect from dust and keep in dry )[>laces. Figure 1 is a highly magnified specimen of common frcen mould. It may be frequently seen on bread, cake, etc The delicate spores at the top, are light and feathery, and are easily detached and blown into the air, where they float as dust plants. The stalks, or stems, grow down into the bread or other articles upon which they feed, just as the roots of our common shrubs grow down into the ground. As these roots take up, or eat up, the nutrient part of the bread nec- essary to their life, the chemical change in the bread is called rotting, or decaying. Yeasts and Bacteria are germs so small, that it would take from 10,000 to 50,000 of them, laid side by side, Fig. 3. £0 make a line one inch in length. They can be seen only by the use of the microscope; hence, are called microbes. Yeast is the plant that produces fermentation, or -working,** in many liquids and moist mixtures, as grap^ 24 DOMESTIC SCIENCE juice, preserves, etc. Yeast will be discussed more fully, later in the course. Figure 2 is a highly magnified group of yeast plants. They multiply by sending out little buds, as you see in the figure, which break off from the larger part and become nev plants, to bud in turn. Bacteria are the smallest and simplest of known living things. Each one is a jelly-like, colorless, and nearly trans- parent cell. Their home is mostly in the upper layers of the earth, but they are carried everywhere by the winc-s, the rain, and the snow. They are in the air we brea^.he, the feed we eat, the water we drink; they are on the bodies of men and animals, in their mouths, under their nails. They re- quire moisture for their growth. Many require heat for their growth, but some grow at a freezing temperature. They multiply rapidly, doubling about every five minutes, under proper conditions of temperature and moisture. As they Fig. 3. grow, some kinds of bacteria throw off poisonous substances; which produce diseases of different kinds. Some kinds of bacteria are harmless. As we cannot tell, readily, the danger- ous kinds, we try to destroy all. All dust and dirt should be destroyed by burning. Dark, damp places are favorable to the growth of bacteria, while fresh air and sunlight are great disinfectants. Figure 3 shows a group of highly magnified bacteria, of various forms and sizes. They, too, multiply by budding, like the yeast olant COOKING 25 Lesson 2.