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.
Tropism is a growth response between a plant and an external stimulus. The stimulus could be weather, touch, time, gravity or light. A positive response is indicated by growth toward a stimulus and a negative response is indicated by growth away from the stimulus. Gravitropism is a plant's growth response to gravity. Typically roots grow down into the ground, and stems and leaves grow up above the ground. If one were to place a plant on its side, it would begin to bend in an upright position.