THE INCUBATION OF SERPENTS. 347 



the night. But for some time after the sun had passed off, and 

 long after the temperature of even those snakes which had been 

 lying in its direct rays and had not moved from their place had 

 fallen to that of the air, and the stones, glass, and boards were 

 cold again, there was a remarkable retention of heat — never rising 

 above what had been lost, but sinking so slowly that it was some- 

 times nearly two hours before that of the surroundings, plus 1'8°, 

 was reached. Thus, after all deductions were made, an apparent 

 maximum of 4*6° was gained. I was entirely at a loss to account 

 for this at first, and was unable to work the matter completely 

 out, even by the end of the six days ; and I regret for this reason 

 more than for any other the stupid interference which put a stop 

 to the incubation. I am almost certain, however, that it was due 

 simply to a storing of the external heat in the eggs, this 

 evaporating slowly afterwards through the mal-conductive mem- 

 brane and the body of the snake ; and that such apparent retention 

 or maximum elevation was purely passive and mechanical. I 

 therefore believe that 1'8° was the highest intrinsic or vital 

 increase which the reptile exhibited. Perhaps I should have 

 explained that the cage was not provided with any artificial 

 heating apparatus, but that the sun shone upon it from about six 

 to ten a.m. — if it shone at all ; very luckily this happened to be 

 the finest part of the day about that period. Beyond this, the 

 cage had only such warmth as a dwelling-room at this time of the 

 year affords, its inmates being hardy European and North 

 American Colubers of several species. 



There could be no doubt of the little serpent's energy and 

 definite purposeful determination in its object. She was a rather 

 small specimen, and though thin and weak she did not leave her 

 charge for a moment, but resented disturbance most strenuously ; 

 she drank a little water which I presented to her in a saucer, but 

 would not go to the bath, nor was she to be tempted with frogs. 

 On several occasions she bit my hands as I busied myself about 

 her with the thermometer ; and I think that those who are 

 familiar with the habits and characteristics of this species will 

 agree with me that such an action is no less phenomenal than 

 the rise of temperature, and that it may be looked upon as 

 indicative of the intense revolution which the reptile's whole 

 nature must undergo at such a period. I have never witnessed 

 or heard of such a proceeding on the part of this singularly 



