HYBERXATION OF IKSF€T^. 459 



is, that no author, as far as my knowledge extend^;, hag 

 kept steadily in view, or indeed has distinctly per- 

 ceived, the difference between torpidity and hyberna- 

 Ison ; or, in other words, between the state in which ani- 

 mals pass the w inter, and their sehclion of a siluation 

 in which they may become subject to that state. 



That the torpidity of insects, as well as of other hy- 

 bernating animals, is caused by cold, is unquestionable. 

 However early the period at which a beetle, for exam- 

 ple, takes up its winter quarters, it does not suft'er 

 that cessation of the powers of active life which we 

 understand by torpidity, until a certain degree of cold 

 has been experienced ; the degree of its torpidity varies 

 with the variations of temperature ; and there can be 

 no doubt that, if it were kept during winter from the 

 influence of cold, it would not become torpid at all — 

 at least this has proved the fact with marmots and dor- 

 mice thus treated; andtheAphisof the rose f^. Rosa-), 

 which becomes torpid in winter in the open air", re- 

 tains its activity and gives birth to a numerous pro- 

 geny upon rose trees preserved in greenhouses and 

 warm apartments. 



But, can we, in the same way, regard mere cold as 

 the cause of the hi/hernation of insects ? Is it wholly 

 owing to this agent, as most writers seem to think — 

 to feelings either of a pleasurable or painful nature 

 j)roduced by it — that prcxiousli/ to becoming torpid 

 they select or fabricate commodious retreats precisely 

 adapled to the constitution and wants of different spe- 

 cies, in which they quietly wait the accession of tor- 



* K}l)er in Geimai's Mag. ikr Enl. ii, 3. 



