66 Animal Temperature as a part of Evolution, 



and lower progressively in each new species the temperature 

 necessary for the production of its chemical phenomena. 



Thus theoretically : — (1) The heat-producing function took 

 its origin in the cooling of our globe, it accommodated itself 

 to and onl^ increased loith it ; (2) the chemical temperatures, 

 in ancient times very high, have always decreased, either in 

 order to produce equilibrium or to adapt themselves to the 

 surrounding medium. 



We may thus divide existing animals into two groups — one 

 making its appearance on the globe in ancient times, the other 

 in modern. The ancient group having ceased its evolution 

 at epoclis still but little cooled, has theoretically only acquired 

 a feeble heat-producing power. The animals of this group 

 which have been continued to our times (such as the Mono- 

 tremata, Marsupialia, Edentata, Amphibia, Chiroptera, and 

 hibernating animals) ought a priori to exhibit a very feeble 

 heat-producing power, the feebleness being proportional to their 

 antiquity. 



The chemical temperature being dependent upon two factors 

 (the surrounding medium and the heat-producing capacity), 

 the actual temperature of these animals, a priori very low, 

 ought to form a scale of species in the order of their appear- 

 ance on the globe. 



Empiricism accords with theory. I take the first two 

 figures of the list which follows from a recent work by 

 M. R. Semon ; the rest are my own : — 



Ornithorhynchus, 25° at an external temperature of 20° ; 

 Echidna, 30° at 19°; Opossum, 33° at 20°; Armadillo, 34° 

 at 16°; Hippopotamus, 35°'3 at 11°; Myopotamus (Coypu), 

 35°-5 at 20° ; Vampire, 35°-5 at 18°; Elephant, 35°-9 at 11°; 

 Marmot, 37°-3 at 20° ; Llama, 37°-6 ; Ass, 37°'7 ; Camel, 

 37°'9; Horse, 3S°. 



In the group of animals whose date of appearance on the 

 globe is recent, on the contrary, the animal having prolonged 

 its evolution into the cold period will have gradually ac- 

 quired a higher heat-producing capacity tending to the main- 

 tenance of the ancient high vital temperatures. These will 

 only have fallen in consequence of adaptation to environment ; 

 in this group their fall will be a measure of their recentness. 



It is this which confirms the following list. Some of the 

 temperatures are the result of single observations ; the ob- 

 servers are different ; their absolute value is very restricted, 

 but suffice to confirm the induction : — 



Bird, 42°; ox, 40°; hare, 39°' 7 ; pig, 39°-7 ; rabbit, 39°-6 ; 

 eland, 39°*4; shr-goat, 39°'3 ; dog, 39°"3 ; cat, panther, 

 38°-9; squirrel, 38°-8; rat,38°-lj monkey, 38°-!; man, 37°-5. 



