252 TEMPERATURE OF ECHIDNA ACULEATA, 



period, it will be convenient to consider first the observations 

 obtained during the Winter separately. 



Hibernation of Echidna. — As previously stated, under the 

 conditions under which I observed Echidna, its hibernation was 

 of a very fitful nature. This fact is well exhibited by the sudden 

 falls and rises of temperature shown in the diagrams giving the 

 winter-temperatures. During the periods of hibernation, the 

 temperatures of the animals remained only slightly higher than 

 the external temperature, following the variation of this like the 

 temperature of a cold-blooded animal. The instances in which 

 the temperatures of Echidna are shown to be actually lower than 

 the external temperatures are due to the occurrence of rises of 

 the latter so rapid that the animals have not warmed-up quickly 

 enough to follow them. The diagrams also show how great are 

 the individual diiferences between the animals as to the extent 

 to which they hibernate during Winter, the only common feature 

 being the fact that none of them ever hibernated continuously 

 for more than a few days at a time. The longest period of hiber- 

 nation shown extended over about ten days; the average period, 

 however, was only two or three days. During these periods, the 

 animals lay inert while undisturbed, and showed no visible 

 respiratory movements. If moved and placed in an awkward 

 position, they very slowly readjusted themselves. 



No doubt the unnatural conditions, under which the animals 

 were living, had much to do with the intermittence of their 

 hibernation. The taking of an animal's temperature, per rectum, 

 twice a day, must have a rather disturbing effect, although 

 specimens which were purposely left undisturbed, during periods 

 of hibernation, did not remain torpid any longer than others 

 whose temperatures were regularly taken. 



The behaviour, during Winter, of the Echidnas under my 

 observation was markedly different from that of the animals 

 observed by Martin, who states that "during Winter, Echidna 

 abandons all attempts at homceothermism and hibernates for 

 four months." The fact that the Winter of Melbourne (where 

 Martin's observations were made) is rather colder than that of 

 Sydney, the average midwinter temperatures being 9*5° and 



