OBSERVATIONS ON INSECTS. 319 



autumn, in places secure from frost, but also throws out round 

 the mouth of its shell a thick operculum formed from its own 

 saliva; so that it is perfectly secured, and corked up, as it 

 were, from all inclemencies. The cause why the slugs are 

 able to endure the cold so much better than shell-snails is, 

 that their bodies are covered with slime, as whales are with 

 blubber.* 



Snails copulate about midsummer ; and soon after deposit 

 their eggs in the mould, by running their heads and bodies 

 under ground. Hence, the way to be rid of them is, to kill as 

 many as possible before they begin to breed. 



Large, gray, shelless cellar snails, lay themselves up about 

 the same time with those that live abroad : hence, it is plain, 

 that a defect of warmth is not the only cause that influences 

 their retreat. 



SNAKE'S SLOUGH. 



There the snake throws her enamel'd skin. 



SHAKESPEARE'S Mids. Night's Dream. 



About the middle of this montH (September) we found, in 

 a field near a hedge, the slough of a large snake, which seemed 

 to have been newly cast. From circumstances, it appeared as 

 if turned wrong side outward, and as drawn off backward, like 

 a stocking, or woman's glove. Not only the whole skin, but 

 scales from the very eyes, are peeled off, and appear in the 

 head of the slough like a pair of spectacles. The reptile, at 

 the time of changing his coat, had entangled himself intricately 

 in the grass and weeds, so that the friction of the stalks and 

 blades might promote this curious shifting of his exuvice. 



Lubrica serpens 



Exuit in spinis vestem. LUCRET. 



It would be a most entertaining sight, could a person be 

 an eye-witness to such a feat, and see the snake in the act of 

 changing his garment. As the convexity of the scales of the 

 eyes in the slough is now inward, that circumstance alone is a 

 proof that the skin has been turned : not to mention that now 

 the present inside is much darker than the outer. If you look 

 through the scales of the snake's eyes from the concave side, 

 viz. as the reptile used them, they lessen objects much. Thus 

 it appears, from what has been said, that snakes crawl out ot 



* Slugs have the property of spinning a slimy thread, whereby tlioy 

 can let themselves down from a height in the manner of spiders. ED. 



