234 TEMPEKATURE OP ECHIDNA ACULKATA, 



In view of this incomplete state of our knowledge of the 

 waking-temperatures of other hibernants, therefore, the conclu- 

 sion that Echidna is the lowest on the scale of warm-blooded 

 animals seems hardly justified. Anatomically, Echidna is indeed 

 the most primitive of mammals, but between the anatomical 

 classification of animals and their physiological functions there 

 is not necessarily a direct relation. With regard to temperature, 

 for example, this is well illustrated by a comparison of birds with 

 reptiles and with mammals. As far as their structure is con- 

 cerned, birds are much more closely related to reptiles than to 

 mammals, and yet their behaviour with regard to temperature is 

 quite different from that of reptiles, and very similar to that of 

 mammals. 



The aim of the present work has been to collect a series of 

 observations of the body-temperature of Echidna under condi- 

 tions which, although they can hardly be called natural, yet 

 underwent no arbitrary, regular variations. The endeavour has 

 also been made, by collecting a large number of data over fairly 

 long periods and at different times of the year, to obtain material 

 from which a more comprehensive idea of the behaviour of 

 Echidna, with regard to temperature, might be gathered. 



It may be stated here (i.) that the Echidnas under my observa- 

 tion hibernated only for very short periods at a time during the 

 winter, (ii.) that, outside the periods of hibernation, their temper- 

 ature kept in the neighbourhood of a value (30°C.) which is con- 

 siderably lower than that of the average temperature of the 

 majority of mammals, and (iii.) that the temperature of the 

 animals was subject to comparatively large variations, and seemed 

 to be affected, to some extent, by the temperature of the air. 



Methods. — The observations recorded in this paper were made 

 upon ten Echidnas, all males, and varying in weight from about 

 600 to about 2000 gms. The animals were kept in a shed of 

 fibro-cement, the floor of the shed being of concrete, and having 

 upon it a layer of sawdust about 5cm. thick. For the first three 

 weeks during which observations were made, the animals were 

 fed upon bread and milk; for the remainder of the time, upon 

 eggs beaten up with milk to which a little sodium citrate had 



