Born February 2, 1869 in Ypsilanti, Michigan. [Died] December 19, 1954. Palo Alto, California. American zoologist. Researched at the University of Chicago (1895-1934). Professor at the same university since 1916. Planaria and hydra were known to regenerate from each piece of tissue when chopped into small pieces, but Child found that regeneration was directional, that is, the head regenerated from the end of the tissue piece closest to the head, and the tail regenerated from the end closest to the tail. To explain this observation, he hypothesized that there was a kind of gradient from head to tail along the axis of the individual, and proposed a theory that this gradient is preserved within each piece of tissue even when the individual is cut into small pieces, and determines the position where organs differentiate. Child considered the actual substance of the gradient to be the concentration gradient of chemical substances. Today, this is called a physiological gradient, and is one of the basic concepts in embryology. He came to Japan as a Rockefeller professor from 1930 to 1931, and lectured at Tohoku University. child |
[生]1869.2.2. ミシガン,イプシランティ [没]1954.12.19. カリフォルニア,パロアルト アメリカの動物学者。シカゴ大学で研究 (1895~1934) 。 1916年以後は同大学教授。ナミウズムシ (プラナリア) やヒドラは,これを細かく刻んでも,それぞれの組織片から個体の再生してくることが知られていたが,彼は再生に方向性のあること,すなわち,組織片の両端のうちで頭部に近かったほうの端から頭が,尾部寄りの側の端より尾が再生することを見つけた。この観察事実を説明するために,個体の軸に沿って頭から尾に向うある種の勾配が存在すると仮定し,個体を小片に切分けても個々の組織片の中でこの勾配は保存され,器官の分化する位置を決定するという理論を発表。勾配の実体として,チャイルドは化学物質の濃度勾配を考えていた。今日,これは生理勾配の名で呼ばれ,発生学における基本概念の一つになっている。 30~31年ロックフェラー派遣教授として来日,東北大学で講義を行なった。 チャイルド
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