52 WESLEY MILLS ON 



terized by drowsiness and no more ; again it was plainly only sleeping, while again it 

 was as profoundly torpid as it ever became. The period of most profound sleep was 

 never reached all of a sudden, biit was preceded by the two states referred to above. 

 Moreover, as the depth of winter approached the sleep became more prolbund, and the 

 reverse with the ai^proach of spring, so that we might represent the depth of the sleep by 

 a rising followed by a falling curve with a rather long flattened top. During the whole 

 of the first period the animal nestled in the straw with which he w^as always provided 

 and when he was most profoundly unconscious but little of him could be .seen often, 

 so completely was he covered. 



Another important matter : The amount of food consumed was directly proportional 

 to the depth of his sleep. Not only did he eat less frequently as a matter of course, but 

 the quantity taken at one time was less. Occasionally when fi;lly hibernating he would 

 awake to fall asleep again, merely after gathering the straw about him a little closer, and 

 not eat at all. His cage always being supplied with food, there was no doubt about his 

 ability to provide himself when so inclined. 



His excretions were also in proportion to the amount of food consumed and especially 

 to the depth of the sleep. The less he ate and particularly the more profoundly he slept 

 the less were his evacuations when he awoke. He never befouled his bed but always 

 left it to void urine and freces. 



During the period of mere drowsiness the animal would be awakened by a gentle 

 rustling against its cage, and even when asleep a noise, etc., would always arouse it ; but 

 when in a torpid condition it could not be thus aroused, but might be handled without 

 being brought to the natural condition, though handling and much less disturbance al- 

 ways caused movement, a phenomenon to be discussed later. 



In the spring of 1891 my woodchuck came out of his winter sleep in a very emaciated 

 condition, and this as iisual increasing after his awakening, he was in a doubtful state ; 

 but the case was soon decided against the animal in consequence of my servant having 

 left him for some time fully exposed to the sun's rays. An autopsy revealed the fact that 

 the animal (a male) was the subject of tuberculosis of the lungs, though possibly but 

 for this exposure he might have lasted another year. 



Through the kindness of Mr. R. F. Rorke, an undergraduate in Medicine of McG-ill 

 University, I became possessed of two specimens of the marmot in the latter part of the 

 summer of 1891. One of these was very large and in fine condition, and his escape soon 

 after arrival has been a frequent subject of regret by me as I hoped to be able, not only 

 to continue the observations, but to make them comparative, as it was my intention to 

 keep both under the same conditions, in fact, in the same cage. But the curiou^s part re- 

 mains to be told. Ihough T kept the remaining woodchuck under exactly the same con- 

 ditions as the animal I had so long had, he did not hibernate for an hour the whole win- 

 ter, though he drowsed and slept enough. 



It has been generally considered that the hibernating condition of animals was de- 

 pendent above all else on the temperature of the surrounding atmosphere. My experi- 

 ments in bats seemed to warrant this conclusion, for whenever the temperature reached 

 the neighbourhood of 45' F. to 40' F., the other conditions being favourable, my specimens 

 began to hibernate. It was also true that my woodchuck was in the deepest sleep 

 during midwinter when the cold is greatest. Whether a bat could be put into a state 



