ARCTOMYS MONAX. 
145 
placed again in its box, where it went to sleep, as soundly as ever, 
until spring made its appearance. That season advancing, and 
the trees showing their leaves, the Woocl-Chuck became as brisk 
and gentle as could be desired, and was frequently brought into 
the parlour. The succeeding winter this animal evinced the same 
dispositions, and never appeared to suffer by its long sleep.” * 
In Rensselaer County in this State, during the summer of 1814, 
Dr. Bachman marked a burrow that he knew to be inhabited by a 
pair of Woodchucks. Early in November he had it opened 
and found the animals lying close together in a nest of dry 
grass about twenty-five feet (7. 62 metres) from the entrance. 
“ They were each rolled up,” he writes, “ and looked somewhat 
like two misshapen balls' of hair, and were perfectly dormant.” f 
In hibernation the temperature of the animal approximates that 
of the surrounding atmosphere, the heart’s action slackens, and 
respiration can only be detected by means of delicate instruments 
devised for the purpose. This latter fact was known to Spallan- 
zani nearly a hundred years ago, for he wrote to Senebier : “ You 
will remember about my Marmot which was so exceedingly lethar- 
gic in the severe winter of 1795 ; during that time I held him in 
carbonic acid gas for four hours, the thermometer marking- -12°, he 
continued to live in this gas which is the most deadly of all . . . 
at least a rat and a bird that I placed with him perished in an 
instant.” 
It is well to observe that different animals exhibit in different 
degrees the physiological process of hibernation ; and that this 
fact is amply illustrated by the representatives of the family to 
which the present species belongs. Animals that are able to pro- 
cure subsistence in the winter season, and those that lay up large 
stores in their nests, do not sleep so continuously, and their leth- 
argy is not so profound as in the case of those species that are 
* Quadrupeds of North America, Vol. I, 1846, pp. 20-21. 
f Ibid., p. 22. 
