1897] NOTES AND COMMENTS 291 
brates by Mr Alexander Sutherland (Proc. Roy. Soc. Victoria, n. s., 
vol. ix., pp. 57-67, pl. 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 29°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 36°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 (Petawrus), with average 35°7° C. Eighty-three 
