48 THE STRUCTURE AND LIFE OF BIRDS cnap, 
of which I shall speak soon. But these also may have 
been to some extent warm-blooded. 
-/ The fact that existing reptiles are cold-blooded, 
while birds have high temperatures, is really no barrier 
between the two classes. There was once a Python 
at the Zoological Gardens which laid eggs, and for 
six weeks sat upon them, at the end of which time 
they were addled, or, at any rate, the young snakes 
in them were dead! But the python had not “sat” 
in vain, for every day her temperature was taken by 
experts, and also that of a male python hard by who 
was subjected to the same conditions. The female had 
an average temperature of 89'07° F., the male of 
86:03° F. The maximum temperatures were for the 
female 92°8° F., for the male 898°. But the great 
difference between warm and cold-blooded animals 
is that the former do not change their temperature 
as that of the air changes. The female python was 
once 16°7° warmer than the surrounding air, the male 
never more than 11°6°. Ina similar case observed in the 
Jardin des Plantes in 1861 the female’s temperature 
once rose 38'7° F. above that of her surroundings. She- 
pythons, therefore, when incubating are not altogether 
the sport of atmospheric changes. Even in mammals 
temperature varies very much, the small ones having 
as a rule the hottest blood. Those of large bulk 
range between 974° and 984°. The sheep is said to 
have a temperature of 104°. The Echidna sends the 
thermometer only to 822°, and the Ornithorhyncus 
only to 762°. In birds the range is considerable, 
' Proceedings of the Zoological Society, 1881, “ The Incubating 
Python,” by W. A. Forbes, 
