ON THE INCUBATION OF THE INDIAN PYTHON. 289 



measured between the coils, as much as 21-5 C. (between 18'0 C. and 

 39-5 C.) or 38-7 F., a difference enormously greater than any we 

 observed. 



It would seem therefore that, if his observations are to be relied on, 

 throughout the case recorded by Valenciennes the female developed a far 

 greater amount of heat than ours did, though she was kept in a cage that 

 was apparently considerably colder*. As in this case more than half the P. Z. S. 1881, 

 eggs hatched out, it may be that the failure of our animal to do the same **' 

 was due to the lack of heat. There is also in our case none of that steady 

 fall in temperature, from the commencement to the close of incubation, 

 observed by Valenciennes. In his case, at the commencement of incu- 

 bation the female had a temperature of 41-5 C. (106*7 F.) between the 

 folds (the highest observed at all), falling at the end to 28 C. (82-4 F.). 

 In our case, the maximum temperature was very nearly obtained on three 

 different occasions. 



The second set of observations, those made here in 1862, are hardly 

 complete enough to allow of much comparison; but throughout that 

 series the differences between the sexes are greater, though the absolute 

 temperatures are considerably lower t than the average ones I obtained. 



Eenewed observations will be required to satisfactorily settle the 

 amount of the increase of temperature a fact of which there can now, 

 I think, be no doubt which is produced in these reptiles by the process 

 of incubation. The average difference of 3 F. which I have obtained is, 

 it may be observed, very nearly identical with that which occurs in the 

 case of the temperature of fever-patients as compared with the normal. 

 And as the increase of heat in an incubating bird is essentially of the 

 same nature as that produced by an inflammation of a tissue, and such is 

 also presumably the case in an incubating reptile, the nearness of the 

 results thus arrived at is, in itself, an argument in favour of the correct- 

 ness of my observations. 



* The extreme temperatures of the air recorded by Valenciennes who took his 

 observations when the cages were coldest, i. e. before the fresh hot water was put in are 

 17'C. and 23 C. (62-6 F. and 73'4 F.) respectively. The temperature of the two 

 cages in which our animals were kept was only on three occasions kss than the highest 

 in Valenciennes' series. 



t Except in the case of one reading of 96 F., taken on the female, which was on 

 that day 20 F. warmer than the male. This observation, however, is, I think, open 

 to doubt. 



