366 DR. P. L. SCLATER ON THE [Dee. 9, 
This pair of Pythons were several times observed in copuld by the 
keeper, in the month of June 1861. Towards the middle of December, 
1861, the female was remarked to be much increased im size, the 
enlargement extending about 8 feet along the body. The keeper, 
knowing that she had not fed for many weeks, imagined this altera- 
tion of size to be the result of disease; and it was only a few days 
before the 13th of January that the true cause of her abnormal 
appearance was suspected. On the morning of the 13th of January 
the keeper found that in the course of the previous night this animal 
had deposited a large mass of eggs, and had taken up a position 
coiled completely round them, so as nearly to exclude them from 
view. The eggs, as we afterwards ascertained, were about 100 in 
number ; they were nearly round in shape, but soft, and soon became 
much compressed, measuring each about 3 inches in diameter. They 
seemed to have been deposited in a circle, probably from the creature 
crawling round, and excluding them one after the other. They 
were not strung together by any membrane, but apparently com- 
pletely separate when excluded, though afterwards fastened into one 
large conical mass, adhering by the viscid outer membrane, and 
pressed together by the weight of the superincumbent mother. 
The Python retained her position coiled round and over the eggs 
more or less constantly until the eggs were eventually removed on 
the 4th of April. During this time she quitted them upon very few 
occasions, and then only temporarily, having passed altogether nearly 
thirty-three weeks without taking food. 
On the 4th of March the Python showed symptoms of being 
about to cast her skin, and was then off her eggs from 9 p.m. until 
7 a.M. on the following morning. During this interval the skin came 
off in shreds (always an unhealthy symptom in snakes), the process 
lasting about 10 hours instead of 3 or 4, as is usually the case with 
these large serpents. 
Knowing the interesting nature of M. Valenciennes’s experiments 
on the temperature of the Python which incubated in the Jardin des 
Plantes at Paris in 1841*, I was anxious to ascertain whether any 
similar increase of temperature was observable in the present case, 
The instruments first employed for this purpose were not sufficiently 
delicate to produce any very reliable results. I therefore applied to 
Messrs. Negretti and Zambra, the well-known optical instrument- 
makers, who provided thermometers expressly adapted for the 
purpose} and kindly attended themselves to assist in making the 
* For an account of these, see ‘Comptes Rendus,’ 1841, xiii. p. 126. 
+ These thermometers are spoken of as follows in the ‘London Review’ for 
March 15th :— 
“Tn testing the heat of the incubating Python and her eggs, it will be readily 
imagined that the most sensitive thermometers would be required to obtain reli- 
able and satisfactory results, not only on account of the possible danger, through 
disturbing and irritating the snake, of her striking and giving the operator a 
lacerated wound with her pointed teeth, but from the desirability of obtaining as 
instantaneous results as possible to avoid the interference of cold drafts of air, 
alterations of the creature’s position, and other cireumstances which must produce 
interferent effect. To Messrs. Negretti and Zambra the highest praise is due for 
