[Effects of low temperatures on the concentration of erythrocytes in newts during winter]

In winter time, specimens of Triturus cristatus carnifex kept at temperature of 5 degrees C show a decrease in the concentration of circulating erythrocytes and marked hypertrophy of the spleen, in comparison to animals raised at 15 degrees C. Thanks to their capacity to accumulate a large number of erythrocytes in the spleen, newts can switch from their condition of a seasonal hyperactivity, maintained by a high concentration of circulating erythrocytes, to hibernation. This is the reason why red blood cell counts made an freshly collects animals during the winter are extremely heterogeneous.