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VII ON THE CAUSES OF THE TORPIDITY OF THE TENREC, (JErina- 



ceus ecaudatuSj Linn.) 



The influence of cold as a cause of hybernation has not been 

 considered essential, on account of an assumed fact, which is 

 altogether incorrect. This fact is that a mammal called the 

 Tenrec, (Erinaceus ecaudatus,~Lm.,) which lives in the Islands of 

 Mauritius, of Madagascar and Bourbon, is torpid under the 

 joined influences of warmth and dry ness. Cuvier says, about the 

 Tenrec : " They are nocturnal animals, remaining in lethargy 

 three months each year, although they inhabit the torrid zone. 

 Moreover, Bruguiere asserts that it is during the time of the 

 greatest heat that they are torpid." Physiologists have admit- 

 ted this fact as true, and they have supposed that warmth and 

 dryness could be, like cold, a cause of torpidity. 



The following facts prove that the torpid sleep of the tenrec 

 takes place from precisely the same cause as that of the 

 hedge-hog, LErinaceus Europeus, Lin.,) and of other hyber- 

 nating mammals : 



1st. The tenrec and the hedge-hog belong to the same 

 family, and they are much alike. 



2d. According to MM. Desjardins, Telfair and Coquerel, and 

 to my own observations, the tenrecs earth themselves, and are 

 torpid from the month of June to the month of November, i. e. 

 during the winter season of the Islands where they live. 



3d. Hybernating animals, belonging to varied species, 

 observed by Pallas, Mangili, Marshall Hall, Berthold, Barkow, 

 and myself, have been found torpid at the temperature of 61 to 

 66 F., (16 to 19 Cs.) Moreover, I have found that dormice, 

 (Mus glis., Lin.) even at a temperature of 6 S to 72 F., (20 to 

 22 Cs.) may become torpid, and I have observed some that 

 were constantly sleeping, during a whole week, at a tem- 

 perature varying from 59 to 68 F. (15 to 20 Cs.) I have 

 stated that hedge-hogs may be torpid during the summer ; 

 in Paris, at a temperature of 68 to 72 F., (20 to 22 Cs.) and 

 lately, in Philadelphia, I have seen a marmot (Arctomys monax, 

 Buff.) torpid, in June, at a temperature of 71 to 73 F. (21.5 to 

 23 Cs.) 



4th. During the time of its torpidity, the tenrec is under 



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