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It has been generally the custom of writers on natural history to take the habits and instincts of animals as the fixed point, and to consider their structure and organization as specially adapted to be in accordance with them.
以动物的习性和本能为切入点，认为动物的结构和组织是专门为适应动物的习性和本能而调整的，这已成为自然史作家的普遍习惯。