TOKPIDITY. 61 



on, althougli sometimes in a very feeble manner. Carbon, 

 consequently, must be evolved. Accordingly, we find car- 

 bonic acid produced in those vessels in which these torpid 

 animals have been confined ; and hence must conclude, 

 that a loss of weight has taken place. 



Such being the preparatory and accompanying pheno- 

 mena of this torpid state, let us now endeavour to discover 

 the cause of these singular appearances. 



In a subject of this kind, so intimately connected with 

 the pursuits of the naturalist and the physiologist, it was to 

 be expected that numerous hypotheses would be }>roposcd, 

 to explain such interesting phenomena. Unfortunately, in- 

 deed, many hypotheses have been proposed, while few, 

 from a connected view of the subject, have ventured to 

 theorise. Perhaps we are not prepai*ed to draw a suffi- 

 . cient number of general conclusions, from the scanty facts 

 which we possess, in order to build any theory. But the 

 following observations may be considered as embracing the 

 principal opinions which have been formed on the subject, 

 and announcing the more obvious causes in operation. 



In an investigation of this sort, it was natural to attempt 

 to trace this singularity of habit in torpid animals to some 

 peculiar conformation in the structiu'e of the organs. Ac- 

 cordingly, we find many anatomists assigning a peculiarity 

 of organization, as a reason why these animals become tor- 

 pid, or, at least, pointing out a structure in torpid animals 

 different from that Avhich is observable in animals that are 

 not subject to this brumal lethargy. 



Pallas observed the thymous gland unusually large in 

 torpid quadrupeds, and also perceived tM^o glandular bodies 

 under the throat and upper part of the thorax, which ap- 

 pear particularly florid and vascular during their torpidity. 



Mangili is of opinion, that the veins are larger in size, 

 in proportion to the arteries in those animals which l^ecome 



