Letter | Published:

Seasonal Changes in the Blood and Thyroid of the Grass Snake, Natrix natrix

Naturevolume 207pages779780 (1965) | Download Citation



CHEMICAL and physical changes in the blood during both natural hibernation and experimental hypothermia have been followed in a number of mammalian species1. Similar investigations do not appear to have been extended in any detail to the reptiles, although fish and amphibians have received some attention. The grass snake is less active during the winter, and this condition is often referred to as torpor. In preliminary investigations carried out in this laboratory during 1961, the blood from five specimens, which had entered normal winter torpor in a vivarium, was analysed in February. The ambient temperature was 7° C and some intermittent activity was observed. In July of the same year eleven specimens were available for analysis, the ambient temperature being 18° C. The results, together with comparable data on the hedgehog1, are presented in Table 1.

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  1. 1

    Kayser, C., The Physiology of Natural Hibernation (Pergamon Press, London, 1961).

  2. 2

    Uotila, U., and Kannas, O., Acta Endocrinol., 11, 49 (1952).

  3. 3

    Barrington, E. J. W., and Matty, A. J., Proc. Zool. Soc. Lond., 124, 89 (1954).

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  1. Department of Zoology, Royal Holloway College, University of London, Englefield Green, Surrey

    • E. J. BINYON
    •  & G. I. TWIGG


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