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Rapid Growth Of Nerve: His discovery of the technique of Tissue culture in 1907, made with nerve cells from which he had observed the growth of nerve fibers, provided his direct experimental evidence. Characteristically, he left the development of Tissue culture technique to others and devoted his efforts to pure research. He made fundamental transplant studies of polarity and asymmetry in embryonic organs and of the control of organ growth.
It has been demonstrated experimentally (in another kind of nerve) by Keith Lucas in 1910, and by others, that the magnitude of impulses in a sensory nerve and the speed of conduction of these impulses along the nerve depend on the particular fiber and on its condition, and not on the magnitude of the stimulus—provided that the nerve responds at all. This principle—the all-or-nonc law—puts a severe limitation on the means that sensory nerves can use to transmit information from sense organs. It means that a nerve fiber cannot show the strength of a stimulus by the strength of its response.
He makes many jerky, kicking movements, which may arise from neurological immaturity, from the rapid growth of nerve centers, or from other internal stimuli. In response to a specific stimulus, such as a light pinch on the knee, the newborn is likely to squirm and show general restlessness. If he is hungry, the same stimulus may produce sucking movements. Intense stimuli tend to evoke both general and specific movements. |
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