ON THE INCUBATION OF THE INDIAN PYTHON. 285 



47. OBSERVATIONS ON THE INCUBATION OF THE P. z. 8.1881, 

 INDIAN PYTHON (PYTHON MOLURUS), WITH p * 96 * 

 SPECIAL REGARD TO THE ALLEGED INCREASE 

 OF TEMPERATURE DURING THAT PROCESS.* 



THE first exact observations of the incubation 06 their eggs by the females 

 of the constricting Serpents included in the genus Python were made, 

 forty years ago, by M. Valenciennes in the Jardin des Plantes at Paris, 

 his account having been published in the 13th volume of the ' Comptes 

 Rendus' for 1841 f. In this case the species observed was Python bivit- 

 tatus : a female, about 10 feet long, which had been in company with a 

 male of the same species of rather smaller size, and with which she had 

 been seen several times in copula, laid at the beginning of May fifteen 

 eggs, round which she coiled herself up, and so remained for fifty-six 

 days, when eight of the eggs hatched, producing young snakes about half 

 a metre in length. During the period of incubation Valenciennes 

 observed a marked increase of temperature in the female, highest at the 

 commencement of incubation and gradually diminishing thence till its 

 close. His observations on the temperature are recorded in a table 

 appended to the memoir already cited ; and to them I shall have further 

 occasion to refer in the sequel. 



In the year 1862, a large female Python sebce laid a number of eggs, and 

 also incubated on them, in this Society's Gardens, as described by Mr, 

 Sclater at length*. The period of incubation lasted 82 days ; at the end 

 of that time the eggs were removed, as none had hatched, and they were 

 evidently decomposing. On examination five or six were found with 

 embryos inside, one of these being eleven inches in length. A few obser- 

 vations on the temperature of the female were taken, that of the male 

 in the same compartment being taken at the same time. In every case, 

 the female w r as found to be several degrees warmer than the male, the 

 difference ranging between 2*8 F. and 12'4 F. when the surface tem- 

 perature was recorded, and between 6-8 F. and 20-0 F. when that 

 between the folds of the animals was measured. 



During the past summer we have again had an opportunity of obser- 

 ving the incubation of a Python in the Society's Gardens. A female 

 Python molurus, about 12 feet long, which had been living in company 

 with two somewhat smaller males (one of this species, the other being a 

 Python Uvittatus}, deposited during the night of June 5th-6th a number 

 of eggs, about twenty. Round these she coiled herself up, in the same 

 way as already observed by Valenciennes and Mr. Sclater, the eggs being 

 nearly entirely concealed from view by her folds. In this position she 



* Proc. Zool. Soc. 1881, pp. 960-967. Bead Nov. 29, 1881. 



t Tom. cit. pp. 126-133. \ P. Z. S. 1862, pp. 365-368. 



