and ears. They found that the tails and ears were significantly shorter in the mice raised in the cold in comparison to the mice raised at warmer temperatures, even though their overall body weights were the same. They also found that the mice raised in the cold had less blood flow in their extremities. When they tried growing bone samples at different temperatures, the researchers found that the samples grown in warmer temperatures had significantly more growth of cartilage than those grown in colder temperatures. See also Bergmann's rule, which correlates latitude with body mass in animals Gloger's rule, which correlates humidity with pigmentation in animals References Physiology Ecogeographic rules