Huxley reasoned that flying vertebrates must have been warm-blooded because flying implies a high rate of metabolism, which in turn implies a high internal temperature.

赫胥黎推断，会飞的脊椎动物一定是温血动物，因为飞行意味着较高的新陈代谢率，而新陈代谢率又意味着较高的内部温度。