386 



SCIENCE PROGRESS. 



variations of which the animal is capable, as the temperature 

 of one individual on a cold morning was found to be only 

 22 . Altogether twenty-seven series of observations were 

 made on fourteen different specimens, the mean temperature 

 being 29*4°. This animal in question thus appears to form 

 a true intermediate stage between the cold-blooded animals, 

 on the one hand, and the warm-blooded on the other. It 

 is able to keep the temperature of its body considerably 

 above that of the environment, provided this be low, or 

 considerably below it provided this be high ; but it is,, 

 nevertheless, affected very largely by these external tem- 

 perature changes, though not to so great an extent as the 

 body temperature of a true cold-blooded animal. 



Upon the marsupials, Sutherland made 126 observations, 

 upon sixteen different species. The mean temperature of 

 all of them was 36*0°, or considerably higher than that of the 

 monotremes, but still appreciably lower than that of the 

 true placental mammals. In the following table are given 

 the mean temperatures of the individuals of each genus 

 examined : — 



Even among these marsupials we see that the mean 

 temperature varies from 34*1° to 36 '6°. The extreme limits 

 of temperature amongst individuals of the same species are 

 even greater. Thus in healthy specimens of the koala, 

 temperatures varying from 34*9° to 38*4°, or by 3*5°, were 

 noticed. Now in healthy placental mammals under normal 

 conditions the limits of temperature rarely exceed one or 

 two degrees. The koala was also influenced by the tem- 

 perature of its environment to a greater extent than is the 

 case with placentals. Thus as a mean of three observations 



