1897] NOTES AND COMMENTS 291 



brates by Mr Alexander Sutherland (Proc. Boy. Soc. Victoria, n. s., 

 vol. ix., pp. 57-67, pi. vi.). For many years past there has been a 

 tendency to diminish or ignore the distinction between the cold- 

 blooded and the warm-blooded types of animal life. The new 

 results, however, seem to confirm the idea that the distinction is a 

 real one, though they show more clearly than ever that several 

 gradations between the two types still survive in the existing world. 

 Cold-blooded animals sometimes develop a capacity for heat-pro- 

 duction in the action of their viscera. Mere digestion, for example, 

 may increase the temperature of a snake from 2° to 4° C, while 

 amatory emotion is known to have the same effect on snakes, 

 lizards, and frogs. But in general this excess of warmth is not 

 great, and it leaves the gap between the warm-blooded and the cold- 

 blooded type quite evident. 



Mr Sutherland's first two experiments were arranged to re- 

 determine to what extent the temperature of a reptile varies with 

 that of its surroundings. He placed some lizards in a tank of 

 water, leaving only their noses uncovered, and then warmed the 

 water at various rates of speed by means of one or more lamps. In 

 each case he found the rise in temperature of the animal and of the 

 water to correspond almost precisely. Other observations also point to 

 the same conclusion, namely, that cold-blooded animals at rest take 

 their temperature almost absolutely from their environment. 



Mr Sutherland next records his experiments with the Monotreme 

 Mammalia. Their low temperature has often been remarked upon. 

 Baron Miklouho-Maclay once determined that of the duck-billed 

 platypus (Ornithorhynchus) to be only 24*8° C, while the average 

 temperature of forty-five specimens of the higher orders of the mam- 

 malia (excluding monotremes and marsupials) observed so long ago 

 as 1825 by John Davy, was proved to be nearly 39° C. — a result 

 subsequently confirmed by Max Fiirbringer. The platypus is, 

 indeed, almost a cold-blooded animal, and the echidna rises very 

 little higher in the scale. Mr Sutherland finds the average tem- 

 perature of Echidna hystrix to be 2 9 "4° C, but it curiously varies : — 

 "An echidna one cold morning was so low as 22° ; another, brought 

 in from the forest in a sack exposed to a fierce midday heat, regis- 

 tered so high as 3 6 "6°. . . . This is an immense range for a mam- 

 mal, and suggests a reptilian want of capacity for temperature 

 regulation." 



As the result of 126 observations, Mr Sutherland determines 

 the average temperature of sixteen different species of marsupials to 

 be 36° C, or three degrees below the average of the higher mam- 

 mals. The marsupial most nearly approaching the monotremes in 

 temperature proves to be the wombat (34*1° C). Next comes the 

 flying squirrel (Petaurus), with average 35*7° C. Eighty-three 



