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THE TEMPERATURE OF ECHIDNA ACULEATA.* 



By H. S. Halcro Wardlaw, B.Sc. 



(From the Physiological Laboratory of the University of Sydney.) 



(With eight Text-figures.) 



Introdnction. — The study of the morphology of Echidna has 

 led to its being classified with the most primitive of mammals. 

 This fact has, perhaps, given rise to the supposition that the 

 functional activities of the animal would share the primitive 

 characters of its structure; and, indeed, Chapman(4) has shown 

 that the behaviour of the muscle of the Echidna towards stimuli 

 resembles more that of the muscle of cold-blooded animals such 

 as the frog, than that of typical mammalian muscle. The 

 observations which had, up to the present, been made of the 

 temperature of Echidna were interpreted as further justifying 

 this supposition. 



The temperatures of reptiles lie within a few tenths of a 

 degree of that of the surrounding air [Pembrey(lO), Richet(ll), 

 Soetbeer{14)], They vary, therefore, from day to day with the 

 changes of the external temperature. 



The temperatures of birds and of nearly all mammals (including 

 marsupials) are subject to little variation (Pembrey, Richet, loc, 

 cif.), and are maintained at levels (36°-45''C.), above which, in 

 most parts of Australia, the temperature of the air rises only 

 during a short season of the year [Hunt(5)]. 



The temperature of Echidna, however, was found to be con- 

 siderably lower and more variable than that of other mammals. 

 N. de Miklouho-MaclayO), who appears to have been the first to 

 observe the temperature of this animal (1879), found the cloacal 



* The work, of which this paper is an account, was carried out in the 

 year 1914, during the author's tenure of a Science Research Scholarship at 

 the University of Sydney. 



