HIBERNATION OF MAMMALS — MATTHEWS 417 



tarded, and this phenomenon has been interpreted as a special adapta- 

 tion to hibernation. During hibernation the heartbeat is slow and 

 weak so that the circulation rate of the blood is reduced ; it is there- 

 fore suggested there is a greater risk of thrombosis— the clotting of the 

 blood in the blood vessels — in hibernating mammals than in active 

 ones. During the active state, on the other hand, the blood must 

 coagulate rapidly in order to prevent fatal loss through a small 

 wound. The cylic change in the clotting rate of the blood may well 

 be, therefore, of particular importance to the hibernating animal. 



Although the experimental removal of the anterior pituitary, with 

 or without the destruction of the cortex of the adrenal glands, to- 

 gether with the injection of insulin, leads to a condition in which the 

 regulation of the temperature is disorganized, and produces a state 

 resembling an artificial hibernation, the role of the different glands 

 remains very obscure — it is not yet known whether many of the changes 

 in them are the causes or the effects of hibernation. Much still re- 

 mains to be discovered — and the study of the physiology of hibernation 

 and temperature regulation in the warm-blooded animals is not of 

 academic interest only. It is probable that an increased understand- 

 ing of the processes involved in hibernation will throw much light on 

 the problem of survival in nonhibernating mammals, including man, 

 when they are subjected to extremes of cold and exposure. 



READING LIST 



Feudmann, D., and Feinschmidt, O. 



1932. Der Winterschlaf. Ergebn. Biol., vol. 8, p. 1. 

 Jaeger, E. C. 



1948. Does the poor-will hibernate? Condor, vol. 50, p. 45. 



1949. Further observations on the hibernation of the poor-will. Condor, 



vol. 51, p. 105. 

 Johnson, G. E. 



1931. Hibernation in mammals. Quart. Rev. Biol., vol. 6, p. 439. 

 Kayser, C. 



1950. Sommeil hibernal. Biol. Rev., vol. 25, p. 255. 

 Lack, D. and E. 



1951. The breeding behaviour of the swift Apus apus. Ibis, vol. 93, p. 501. 

 Pabkeb, H. W., and Boeseman, M. 



1954. The basking shark in winter. Proc. Zool. Soc. London, vol. 124, p. 185. 

 Pearson, O. P. 



1947. The rate of metabolism in some small mammals. Ecology, vol. 28, 

 p. 127. 

 SUOMAI.AINEN, P., and Leiito, E. 



1952. Prolongation of the clotting time in the hibernating hedgehog. Arch. 



Soc. "Vanamo," vol. 6, No. 2, p. 94. 

 Suomalainen, p., and Sxtvanto, I. 



1953. Studies on the physiology of the hibernating hedgehog. Ann. Acad. 



Sci. Fenn. IV, Biologica, p. 20. 



