1862.] INCUBATION OF PYTHON SEB. 367 
necessary experiments. The compartment of the Reptile-house in 
which the Python is kept being warmed with hot-water pipes, and 
the temperature of snakes varying, as is well known, with that of the 
surrounding medium, it seemed to me that the only mode of obtaining 
reliable results was by comparison of the heat of the incubating female 
Python with the heat of the non-incubating male, in the same com- 
partment of the Reptile-house. It appeared to me that any decided 
difference observable between these two animals, subject to exactly the 
same external conditions, could be only attributable to the incubation. 
Our first experiments with Negretti and Zambra’s instruments were 
made on February 12th, and gave a difference of 2°-8 of Fahrenheit’s 
scale in favour of the female, when the temperatures were taken at 
the surface of the body. When the temperature was examined 
between the folds of the bodies of the respective animals, the dif- 
ference was found to be increased to 6°°8. The experiments were 
repeated on the 23rd of February, the 2nd of March, the 9th of 
March, and the 16th of March, with varying results, but always 
showing an increased temperature of greater or less amount in the 
case of the incubating female, as the following Table will show :— 
Differ- 
ence. 
Temperature 
Date. —_| of air in den. 
Temperature of male. Temperature of female. 
Feb. 12 58°°6 On surface.. 70°2 | On surface.. 73°00 | 2°8 
Between folds 74°°8 | Between folds 81°°6 | 6°8 
Feb. 23 65°°4 On surface.. 71°8| On surface.. 75°4 | 3°6 
Between folds 74°:0 | Between folds 83°2 | 9°2 
March 2 60°°0 On surface.. 71°6| On surface.. 84°°0 |12°°4 
Between folds 76°0 | Between folds 96°-0 |20°-0 
March 9 61°°0 On surface.. 72°83) On surface... 79°5 | 6%7 
Between folds* ....| Between folds 86°°5 
March 16] 66°0 On surface.. 72°4 | On surface... 77°°6 | 5°2 
Between folds 77°°6 | Between folds 86°0 | 8°-4 | 
These observations were made on the different occasions by Mr. 
Bartlett, Mr. Negretti, Mr. Zambra, Mr. E. W. H. Holdsworth, 
F.Z.S., and myself. 
On the 4th of April the eggs were evidently decomposing, and 
gave forth a very strong and nauseous odour. As the snake, which 
haying manufactured expressly for these experiments the most sensitive and most 
perfect thermometers ever constructed. In less than three seconds the quick- 
silver will rise or fall from one end of the scale-tube to the other; and although 
a longer time than this has always been allowed by the reptiles in the experiments 
made, it was most desirable to be provided with efficient means against any 
emergencies. 
“The total length of the tube is 13 inches, and the bore, by actual measure- 
ment, was found to be less than the =;4>th of an inch in diameter ; in the experi- 
ments the motion of the mercury in it was watched with a powerful hand-lens or 
magnifier. The range of the scale is ftom 30° to 105°; the length of the bulb, or 
reservoir for the mercury, 3 inch, its diameter } inch; it is made extremely thin, 
so as to insure the greatest sensitiveness hy the quickest possible transmission of 
temperature.” 
* Not observed, the male being very restless. 
