M. Flourens on the action of Cold on Animals. 1 1 1 



months after. It often happens that a body which at first 

 produces only sounds dull and difficult to obtain, ends by vi- 

 brating with such facility and energy that it bursts in pieces 

 with the slightest agitation. Hence it seems to follow, that, in 

 the act of solidification, many of the particles were caught and 

 fixed in positions which they afterwards tend to abandon, and 

 that they do not attain a state of equilibrium till after a long 

 time. If, for example, we form in a mould a circular disc of 

 sulphur, and try to make it sound immediately after it is cold, 

 we shall not succeed ; but at the end of some days we may 

 elicit from it some dull sounds; if we then determine the 

 number of vibrations obtained by any mode of division, and 

 then lay the disc by for one or two months, we shall find that 

 it will sound with extreme facility, and that the number of 

 vibrations is much greater, the sound being raised more than 

 a tone. It is well known that sulphur which has been melted 

 does not recover when it is solid the properties which it pre- 

 viously possessed, but it was never conjectured that entire 

 months, and perhaps even a longer period, was necessary for 

 this purpose. 



Art. XII. — On the Effects of' the action of Cold on Animals, 

 as exhibited in their Hybernation and Lethargy. By M. 

 , Flourens, Member of the Academy of Sciences.* 



Every person is aware of the important function which is 

 performed in the economy of the universe by the unequal dis- 

 tribution of heat. It is this which determines climates ; it is 

 upon this that the seasons depend ; and it is from this that cli- 

 mates and seasons derive that infinite variety of animal and 

 vegetable productions by which they are characterized. 



In order that an animal or a vegetable may live, — in order 

 that either of them may grow and reproduce, — a certain degree 

 of tempejrature is necessary ; and this temperature varies for 

 each species of plant or animal, so that, in passing from one 

 place to another, we have a new temperature, consequently a 



" Read at the public sitting of the Academy on the 15th June 1829, 

 and translated from the Revue Enc^clopediqne, September 1*829, p. 637-551: 



