HIBERNATION IN MAMMALS— LYMAN and CHATFIELD 



89 



'R 



Fig. 5. — Hedgehog. Continuous record (Experiment 327) of heart rate and body temperature 

 (Tr = rear skin temperature), showing hedgehog going into, in, and coming out of deep hiberna- 

 tion three times in five days. Times of events as indicated numerically on the graph are as fol- 

 lows : 1. 14:00—3/29/53. 2. 03:00—3/30/53, 03:00 3/31/53. 3. 12:00—3/31/53. 4. 01:00- 

 13 : 00—4/1/53. 5. 17 : 00—4/1/53. 6. 18 : 00—4/2/53. 7. 06 : 00—4/2/53, 10 : 00-4/3/53. 8. 12 : 00 

 —4/3/53. (From Dawe and Morrison, 1955.) 



varying from 4 to 21 /minute in a group of 21 golden hamsters hibernating at 5° C, 

 with most hamsters having a rate of 8 to 9/mii'iute. Later Lyman'^ using chroni- 

 cally implanted electrodes decided that hamsters with the faster heart rates were 

 either entering or waking from hibernation, and that the rate was never over 

 15 beats/minute in deep hibernation. 



Auriculo-ventricular dissociation has been frequently described in hibernating 

 animals or animals waking from hibernation.'^-' "- ^■*' " It was also occasionally but 

 not invariably observed by Chatfield and Lyman'° (fig. 6). In this regard it is of 

 interest that in non-hibernating animals whose body temperature has been lowered 



■A- 



Q s 



2 SEC 



^>A-V\r- 



ww 



6 



~^wV-^ ^w1/ Wl --^wV 



Fig. 6. — Ink writer record of the electrocardiogram of a hamster early during the process of 

 arousal. Letters indicate components of electrocardiogram. A. showing A-V dissociation early 

 during arousal ; B. a few minutes later a normal rhythm has been attained. 



