266 HIBERNATION. 



quantity of oxygenated air necessary for the purposes of 

 extremely slow, but not totally extinct, respiration. If this 

 orifice be covered over with a coat of wax or varnish, so that 

 all possible connection with external air be excluded, animal 

 life becomes altogether extinguished, never to be again re- 

 stored. We have observed this minute puncture in the 

 winter covering of the H. ericetorum and some others ; and 

 it is probable that all whose aperture is closed during the 

 cold season only, are furnished with this beautiful apparatus 

 for the preservation of life." * I recommend you to exa- 

 mine into these statements ; and, if your own observations 

 confirm them, they will materially alter some inferences 

 which have been drawn from Gaspard's experiments, and 

 adopted by us, in reference to the total cessation of the 

 action of the lungs and heart. Helix pomatia does not reach 

 this northern latitude ; but I have examined, too carelessly, 

 however, the epiphragm of Helix aspersa during its hyber- 

 nation, and always find a small aperture in it ; and also, in 

 the aquatic tribes, I find a larger hole in their thin winter 

 operculum, intended, assuredly, to keep up the commu- 

 nication between the pulmonary cavity and the circumam- 

 bient medium in their season of repose. 



There is something admirable in this curious adaptation 

 of the economy of the hybernating creatures to their situa- 

 tions ; for otherwise they could not live beyond a single 

 summer in the countries which they now inhabit with impu- 

 nity to themselves. If, during their active state of exist- 

 ence, you were to keep a Limneus, or any other aquatic 

 pulmoniferous species, immersed in water for only one short 

 day, or even for little more than an hour, it would die irre- 

 coverably; but it remains under water, perhaps with the 

 surface frozen over, for three or four months uninjured, 

 when the system has been prepared, in autumn, for the 

 change. -j- And so of the land kinds : they perish if deprived 

 of air for a few hours only in summer, or if exposed to an 

 artificial cold not lower than the cold of winter ; but in a 

 state of hybernation they respire, if any, such a small quan- 

 tity of air as is not to be appreciated, and brave our longest 

 and severest frosts without peril and without pain. " O 

 Lord, how glorious are thy works ! thy thoughts are very 

 deep!" 



Have patience with me while I bestow on you a little 

 more of my tediousness in the notice of one or two points 



* Manual of Land and Fresh-water Shells, p. 46. 

 t Encyclop. Method, i. 296. 



