As the members of a given generation age, their instinct of social conservation becomes stronger, which inevitably and necessarily brings them into conflict with the normal attribute of youthâinnovation. Other important theorists of the 19th century were John Stuart Mill and Wilhelm Dilthey.
Plants require more than just water and sunlight to grow. They also require many nutrients found in the soil. One of the most important nutrients required for plant growth is nitrogen. Nitrogen is used to build plant proteins and nucleic acids, including DNA.
Nitrogen is one of the most important chemical elements for plants. If there is not enough nitrogen available in the soil plants look pale and their growth is stunted. Nitrogen fixing plants are called legumes. Legumes - and all peas and beans are legumes - are plants that work together with nitrogen fixing bacteria called Rhizobia, to fix nitrogen. The Rhizobia chemically convert the nitrogen from the air to make it available for the plant. Legume plants live in a symbiotic relationship with the nitrogen fixing bacteria - the Rhizobia live in nodules in the plant's roots. This way the plant can look after its own nitrogen needs. Fertilizer is not required.