A doffer is someone who removes bobbins, pirns or spindles holding spun fiber such as cotton or wool from a spinning frame and replaces them with empty ones. Historically, spinners, doffers, and sweepers each had separate tasks that were required in the manufacture of spun textiles. From the early days of the industrial revolution, this work, which requires speed and dexterity rather than strength, was often done by children. After World War I, the practice of employing children declined, ending
For a plant organ to bend in response to a stimulus, differential growth of cells on either side of the organ is required. For example, for the stem of a plant to bend toward a light source, cells on the shaded side of the stem near the shoot tip must elongate faster than cells on the lighted side.
Tropisms are usually named for the stimulus involved and may be either positive (towards the stimulus) or negative (away from the stimulus). Phototropism. Phototropism is the growth response of a plant in response to light direction. Different parts of a plant exhibit different reactions to light.Stems exhibit positive phototropism while most roots exhibit negative phototropism.higmotropism is the growth response of a plant to physical contact (touch). Plants that cling to physical structures such as walls exhibit positive thigmotropism. Hydrotropism is the growth response of a plant to water.