962 ON THE INCUBATION OF THE INDIAN PYTHON. [NoV. 29, 



The observations are given in extenso, as we took them, in Table I. 

 (p. 964). In Table II. (p. 967) I have given the average temperatures 

 of the two (Snakes, as deduced from these observations, as well as the 

 difference for each set of readings in the temperature in the two sexes. 

 In the diagrams (figs. 1 and 2, p. 963) I have recorded these averages 

 in a graphic form, the upper line marking the average temperature be- 

 ttveen the folds and the middle line the average on the folds, whilst the 

 lowest one indicates the temperature of the air in the respective cages. 

 This last curve is nearly identical in the two cases, that in the male's 

 cage averaging, however, a trifle higher. Although this is the case, it 

 will nevertheless be observed that both the temperature-curves of the 

 female are higher than the corresponding ones for the male, especially 

 the upper one. All four are clearly influenced by the variations in 

 the external medium, the maxima temperatures of the snakes' bodies 

 being attained when the air is hottest or nearly so. 



Not only are the temperature-curves of the female higher, but, as 

 shown by their less amount of angularity, the tem.perature of the 

 female continues more constant throughout the time observed. This, 

 no doubt, may in part be due to the fact of the female being in a 

 condition of repose throughout, with no variations pi'oduced by 

 exercise, the assimilation of food, or other causes. 



Taking the averages of the first four columns of Table II., we get 

 respectively 82°'98 F. and 86°*03 F. as the temperature of the male, 

 and 84°-38 F. and 89°-07 F. as that of the female, according to 

 whether the temperature is taken on the surface or between the folds. 

 These figures give a difference of 1°'4 F. and a little over 3^-0 F., 

 the difference being in each case in favour of the female. 



The maxitna readings obtained were, as may be seen from Table I., 

 89°-6 F. (July 4) and 89°-8 (July 1.5) for the male (surface and 

 folds), and 8y°-8 F. (July 15) and 92°-8 F. (July 1) for the female. 

 The maximum observed by Valenciennes was 41""5 C. (106°"7 F.), 

 or nearly 14° higher than the highest I observed. 



The greatest difference between the temperature of the air and 

 that of the surface of the two Snakes was b'"3 F. (on June 16th) in 

 the case of the male, and 9'^'6 F. (on June 18th) in the case of the 

 female. The greatest differences between the air and the coils were 

 also observed on the same days, and amounted to ll°-6 F. in the 

 case of the male, 16°' 7 F. in the female. Valenciennes found on 

 one occasion the difference, as measured between the coils, as much 

 as 21°-o 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 deve- 

 loped a far greater amount of heat than ours did, though she was 

 kept in a cage that was apparently considerably colder '. As in this 



' The extreme temperatures of the air recorded by Valenciennes— Trbo took his 

 oliservations when the cages were coldest, i. c. before Ihe fresh hot water was put 

 in— are 17° C. and 23° 0. (62°-6F. and 73°-4F.) respectively. The temperature 

 of the two cages in which our animals were kept was only on three occasions 

 less than the highest in Valenciennes' series. 



