UNIVALVE MOLLUSCANS. 289 



produce upon it, if not provided against. But 

 at a destined period, often when the range of the 

 thermometer is high, not stimulated by a cold 

 atmosphere, except, perhaps, by the increasing 

 length of the night, at the bidding of some secret 

 power, it sets about erecting its winter dwelling, 

 and employing its foot both as a shovel to make 

 its mortar, as a hod to transport it, and a trowel 

 to spread it duly and evenly, at length finishes 

 and covers in its snug and warm retreat ; and 

 then still further, to secure itself from the action 

 of the atmosphere, with the slimy secretion with 

 which its Maker has gifted it, fixes partition 

 after partition, and fills each cell formed by it, 

 with air, till it has retreated as far as it can from 

 every closed orifice of its shell and thus barri- 

 cades itself against a frozen death. Again, in the 

 spring, when the word is spoken awake, thou 

 that sleepest it begins immediately to act with 

 energy, it reinspires, as above related, the air 

 stored in its cells, bursts all its cerements, 

 returns to its summer haunts, and again lays 

 waste our gardens. 



We may observe here, with respect to this and 

 all hybernating animals, a beautiful relation and 

 correspondence between their habits and their 

 functions. Their official duty is to remove su- 

 perfluities and nuisances, to prevent vegetable 

 substances from encroaching too much upon 

 each other, to remove entirely those that are 

 VOL. i. u 



