254 EVOLUTION AND DISEASE. 
frog, its temperature be raised to 36° by carefully warm- — 
ing the water in which the frog is placed it will succumb. 
Such facts as these throw great light upon the re- 
striction of diseases to particular groups of animals, and 
it explains the readiness with which the tubercle bacillus 
flourishes in man, for experimentally it has been found 
to develop most luxuriously at a temperature of 37° to 
39° Cent. This would serve to explain the rarity of 
tubercular lesions in cold-blooded animals. 
Up to the present time tubercle has only twice been 
recorded in reptiles. The first specimen I observed in a 
large Python (Python molurus). The nodules in the 
various organs contained bacilli in large numbers. In 
this instance I am of opinion that the reptile contracted 
the disease from eating tubercular birds. Mr. W. K. 
Sibley reported a case of tuberculosis which he found in 
a snake (7vopidonotus natrix). As the tubercle bacillus 
flourishes at a temperature of 37°-39° Cent. it at first 
seems difficult to account for tubercular lesions in snakes. 
In a valuable series of observations made by Mr. 
Forbes! on an incubating python at the Zoological 
Gardens, the temperature of the male was found to 
vary from 28°-30° C.; the temperature of the female 
under the same conditions of external warmth was 
29°-31'°6° C. These observations were made in July, 
and the greatest temperature recorded between the folds 
of the male was 32° C.; for the female, 33°8° C. It is 
also of interest to find that the temperature of the 
pythons, taken between the folds, was higher than the 
surrounding air, sometimes as much as 6°4° C. in the 
* “ Collected Papers, 1885,” p. 285. 
