378 Mr, J. BlackwalFs Ornithological Notes. 



atmosphere, the two dormice in the cage invariably placed them- 

 selves in their usual posture of repose, when sleep ensued, which 

 gradually lapsed into torpidity, accompanied with all the cus- 

 tomary symptoms, such as decreasing circulation, respiration, tem- 

 perature and irritability. While in a state of transition the re- 

 spiration became intermittent, and, with the circulation, ulti- 

 mately ceased to be apparent. The temperature of the skin 

 slowly descended to that of the atmosphere or nearly so, and the 

 nervous irritability diminished so greatly that loud and sudden 

 sounds, whether grave or acute, produced no sensible effect; 

 punctures also with sharp instruments, and slight electric shocks 

 and sparks given by means of a Leyden jar and an electrophorus, 

 merely occasioned a degree of muscular contraction so small as 

 scarcely to be discerned ; but the repeated application of exter- 

 nal stimuli causing bodily pain, exposure to a current of hot or 

 cold air, or to a high degree of temperature alone, at all times 

 prevented the animals from becoming torpid, and when torpid 

 speedily revived them. 



The hedgehog, Erinaceus europaus, long-eared bat, Plecotus 

 auritus, common wasp, Vespa vulgaris j flesh fly, Musca vomitoria, 

 house fly, Musca domestica, peacock butterfly, Vanessa io, and 

 tortoise-shell butterfly, Vanessa urticcs, when found in winter in a 

 torpid state, I have frequently restored to animation by subject- 

 ing them to a high temperature, perfect torpidity having been 

 again induced on submitting them to the requisite degree of cold. 



In the year 1829 I captured several specimens of the large 

 aquatic beetle, Dyticus marginalis, for the purpose of making 

 some observations and experiments relative to the structure and 

 use of the cup-shaped suckers, with which the males have the 

 tarsi of the first and second pairs of legs provided on the under 

 side, and putting them into an earthenware vessel containing 

 water, I supplied them during several weeks with raw flesh, 

 which they devoured greedily. The month of December in the 

 same year terminated in severe frost ; the maximum temperature 

 of the last week was 37", the minimum 16°* 5, and the mean 

 38°* 75; consequently the water in the earthenware vessel was 

 frozen into a solid mass of ice, and it remained in that state for 

 some days, yet, on being gradually thawed, the beetles resumed, 

 and long continued to exercise their customary functions. 



From the foregoing experiments it appears that birds are not 

 liable to be re^ndered torpid on being exposed to the same agency 

 which quickly induces torpor in various animals known to pos- 

 sess a constitutional proneness to that state of lethargy. It is 

 obvious therefore that they must differ physiologically from those 

 animals ; and I am disposed to think that the legitimate infer- 

 ence to be deduced from the facts is, as I have already stated, 



