Handbook of bacteriology for nurses / [Harry Wardwell Carey].

  • Carey, Harry Wardwell, 1875-1935.
Date:
1930
Catalogue details

Licence: In copyright

Credit: Handbook of bacteriology for nurses / [Harry Wardwell Carey]. Source: Wellcome Collection.

    48/294 (page 44)
    FUNCTION OF BACTERIA. With bacteria so widely distributed on the earth, the question arises as to their use or function in the world. We are accustomed to think of bacteria solely as the cause of disease, and off-hand we would say that this was their chief function. This is not true by any means, for instead of being harmful to life they are very beneficial; in fact, life could not be maintained without them. The causation of disease is a function limited to a small group of micro-organisms, and is of lesser importance. The much more important use of bacteria relates to their ability to produce substances called ferments or enzymes which bring about chemical reactions without entering into the reaction them- selves. They can break down proteid substances (pro- teolytic enzymes), fat, and carbohydrates, into simpler chemical compounds and chemical elements. The plants which form the food of animals would soon be exhausted unless they could obtain proper nutriment to sustain life and reproduce their kind. They live mainly upon carbon and nitrogen in the form of nitrates, which would soon be consumed from the soil unless the supply were continually replenished. Now, the source of carbon and nitrogen is the excre- tions and secretions of animals, which contain these elements in combination with other elements. By the action of bacteria the complex animal matter is decom- posed into the chemical elements that compose it. In this way the plants derive their carbon and nitrogen from the soil. Within the body the bacteria carry on much the same activities. The digestion and absorp-